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FEDER funds through the POCI—COMPETE 2020—Operational Program Competitiveness and Internationalization in Axis I—Strengthening research, technological development and innovation (Project No. 029114). This work was also supported by the European Regional Development Fund through the “Programa Operacional Regional do Centro (Centro 2020)—Sistema de Apoio à Investigação Científica e Tecnológica—Programas Integrados de IC&DT” (Project Centro-01-0145-FEDER-000019—C4—Centro de Competências em Cloud Computing. Associate Laboratory Institute for Health and Bioeconomy—i4HB (project LA/P/0140/2020) which are financed by National Funds from FCT/MCTES. The microscopy facility used in the development of this work is part of the PPBI-Portuguese Platform of BioImaging and is partially supported by the Project POCI-01-0145-FEDER-022122. Publisher Copyright: © 2023 by the authors. The Six Transmembrane Epithelial Antigen of the Prostate 1 (STEAP1) protein has been indicated as an overexpressed oncoprotein in prostate cancer (PCa), associated with tumor progression and aggressiveness. Taxane-based antineoplastic drugs such as paclitaxel, docetaxel, or cabazitaxel, have been investigated in PCa treatment, namely for the development of combined therapies with the improvement of therapeutic effectiveness. This study aimed to evaluate the expression of STEAP1 in response to taxane-based drugs and assess whether the sensitivity of PCa cells to treatment with paclitaxel, docetaxel, or cabazitaxel may change when the STEAP1 gene is silenced. Thus, wild-type and STEAP1 knockdown LNCaP and C4-2B cells were exposed to paclitaxel, docetaxel or cabazitaxel, and STEAP1 expression, cell viability, and survival pathways were evaluated. The results obtained showed that STEAP1 knockdown or taxane-based drugs treatment significantly reduced the viability and survival of PCa cells. Relatively to the expression of proliferation markers and apoptosis regulators, LNCaP cells showed a reduced proliferation, whereas apoptosis was increased. However, the effect of paclitaxel, docetaxel, or cabazitaxel treatment was reversed when combined with STEAP1 knockdown. Besides, these chemotherapeutic drugs may stimulate the cell growth of PCa cells knocked down for STEAP1. In conclusion, this study demonstrated that STEAP1 expression levels might influence the response of PCa cells to chemotherapeutics drugs, indicating that the use of paclitaxel, docetaxel, or cabazitaxel may lead to harmful effects in PCa cells with decreased expression of STEAP1. publishersversion published

Enzymes are widely applied in different industries, like pharmaceutical, food, biofuel, and waste valorization. However, the enzyme operating conditions are very limited. So, in most industrial processes, enzymes are not efficient, due to the use of harsh conditions, like organic solvents, extreme pH, and temperature. Immobilization arises as a way to overcome the process restrictions by offering better stability, activity, and improved recovery of enzymes. Physical adsorption into a solid support is a simple method to achieve enzyme immobilization and is compatible with different materials, like gellan gum. Tyrosinase is an essential enzyme for the biosynthesis of melanin, flavonoids, and l-DOPA, which is a drug used by the pharmaceutical industry to treat Parkinson’s disease. Therefore, it is important to develop an easy and simple method for tyrosinase immobilization that will allow high efficiency and reusability, making the melanin biosynthesis more cost-effective. In the laboratory experiment of the enzymatic biotechnology class, nickel-cross-linked gellan microspheres were prepared and characterized by the students and used as a solid support for tyrosinase immobilization. The reaction catalyzed by tyrosinase was detected by visual observation. This experiment allows students in the biotechnology field to understand the importance of the immobilization process in catalysis since the industry is exploring environmentally friendly processes and also the impact on enzyme efficiency when catalyzing a reaction. Moreover, it helps the students to acquire laboratory handling in the preparation of immobilized systems, while developing their creativity and innovative ability to overcome problems in the enzymatic biotechnology field.

Catechol-O-methyltransferase (COMT) has been involved in a number of medical conditions including catechol-estrogen-induced cancers and a great range of cardiovascular and neurodegenerative diseases such as Parkinson’s disease. Currently, Parkinson’s disease treatment relies on a triple prophylaxis, involving dopamine replacement by levodopa, the use of aromatic L-amino acid decarboxylase inhibitors, and the use of COMT inhibitors. Typically, COMT is highly thermolabile, and its soluble isoform (SCOMT) loses biological activity within a short time span preventing further structural and functional trials. Herein, we characterized the thermal stability profile of lysate cells from Komagataella pastoris containing human recombinant SCOMT (hSCOMT) and enzyme-purified fractions (by Immobilized Metal Affinity Chromatography—IMAC) upon interaction with several buffers and additives by Thermal Shift Assay (TSA) and a biological activity assessment. Based on the obtained results, potential conditions able to increase the thermal stability of hSCOMT have been found through the analysis of melting temperature (Tm) variations. Moreover, the use of the ionic liquid 1-butyl-3-methylimidazolium chloride [C4mim]Cl (along with cysteine, trehalose, and glycerol) ensures complete protein solubilization as well as an increment in the protein Tm of approximately 10 °C. Thus, the developed formulation enhances hSCOMT stability with an increment in the percentage of activity recovery of 200% and 70% when the protein was stored at 4 °C and −80 °C, respectively, for 12 h. The formation of metanephrine over time confirmed that the enzyme showed twice the productivity in the presence of the additive. These outstanding achievements might pave the way for the development of future hSCOMT structural and biophysical studies, which are fundamental for the design of novel therapeutic molecules.

STEAP1 is a cell surface protein of the STEAP family whose main function focuses on intercellular communication and cell growth. STEAP1 is considered a promising putative biomarker and a candidate target for prostate cancer treatment. For specific and selective detection of STEAP1, a molecularly imprinted polymers (MIP) was developed on a screen-printed electrode (C-SPE) whose surface was modified with a nanocomposite based on carbon nanotubes decorated with dendritic platinum nanoparticles (CNTs- PAH /Pt). Then, the MIPs were produced on the modified C-SPE by electropolymerization of a mixture of STEAP1 and a monomer (pyrrole-2-carboxylic acid). Then, the protein was removed from the polymeric network by enzymatic treatment with trypsin, which created the specific template cavities for further STEAP1 detection. Electrochemical techniques such as EIS and CV were used to follow the chemical modification steps of C-SPE. The analytical performance of the biosensor was evaluated by SWV in PBS buffer and in lysates of neoplastic prostate cancer cells (LNCaP) extracts. The MIP material showing a linear range from 130 pg/ml to 13 µg/ml. Overall, the biosensor exhibits essential properties such as selectivity, sensitivity and reproducibility for its application in medical and clinical research diagnosis and/or prognosis of prostate cancer., The authors acknowledge the support from by the Health Sciences Research Centre CICS-UBI (UIDB/00709/2020 and UIDP/00709/2020), the Applied Molecular Biosciences Unit UCIBIO (UIDB/04378/2020 and UIDP/04378/2020) and the Associate Laboratory Institute for Health and Bioeconomy–i4HB (project LA/P/0140/2020) which are financed by National Funds from FCT/MCTES. Jorge Barroca-Ferreira’s individual PhD FCT Fellowship (SFRH/BD/130068/2017). Rui S. Gomes acknowledge is PhD in Doctoral Program in Biomedical Engineering (PRODEB) from Faculty of Engineering, Porto University, info:eu-repo/semantics/publishedVersion

Currently, the lack of reliable strategies for the diagnosis and treatment of cancer makes the identification and characterization of new therapeutic targets a pressing matter. Several studies have proposed the Six Transmembrane Epithelial Antigen of the Prostate 1 (STEAP1) as a promising therapeutic target for prostate cancer. Although structural and functional studies may provide deeper insights on the role of STEAP1 in cancer, such techniques require high amounts of purified protein through biotechnological processes. Based on the results presented, this work proposes the application, for the first time, of a fed-batch profile to improve STEAP1 biosynthesis in mini-bioreactor Komagataella pastoris X-33 Mut+ methanol-induced cultures, by evaluating three glycerol feeding profiles-constant, exponential, and gradient-during the pre-induction phase. Interestingly, different glycerol feeding profiles produced differently processed STEAP1. This platform was optimized using a combination of chemical chaperones for ensuring the structural stabilization and appropriate processing of the target protein. The supplementation of culture medium with 6 % (v/v) DMSO and 1 M proline onto a gradient glycerol/constant methanol feeding promoted increased biosynthesis levels of STEAP1 and minimized aggregation events. Deglycosylation assays with peptide N-glycosidase F showed that glycerol constant feed is associated with an N-glycosylated pattern of STEAP1. The biological activity of recombinant STEAP1 was also validated, once the protein enhanced the proliferation of LNCaP and PC3 cancer cells, in comparison with non-tumoral cell cultures. This methodology could be a crucial starting point for large-scale production of active and stable conformation of recombinant human STEAP1. Thus, it could open up new strategies to unveil the structural rearrangement of STEAP1 and to better understand the biological role of the protein in cancer onset and progression.

The present work shows the application of nickel- and magnesium-crosslinked gellan microspheres in ionic and affinity capture strategies to directly extract hSCOMT from the complex Komagataella pastoris lysate through a simple batch method. Both formulations present similar morphology, but nickel–crosslinked microspheres present higher crosslinker content and smaller diameters. Four different capture strategies were established, by manipulating the ionic strength, pH, temperature and competing agents' presence. The most promising results for hSCOMT capture and clarification were obtained employing an ionic strategy with nickel-crosslinked microspheres and an affinity strategy with magnesium-crosslinked microspheres at 4 °C. The bioactivity results (200%) and purification degree (70%) of hSCOMT captured by the ionic strategy were more satisfactory probably due to the soft ionic conditions used (100 mM NaCl). For the first time, the gellan polysaccharide versatility was demonstrated in the microsphere application for the direct capture of hSCOMT from a complex lysate, simplifying isolation biotechnological procedures.

Membrane-bound catechol

The emergence of new psychoactive substances has earned a great deal of attention, and several reports of acute poisoning and deaths have been issued involving, for instance, synthetic opiates. In recent years, there have been profound alterations in the legislation concerning consumption, marketing, and synthesis of these compounds; rapid alert systems have also been subject to changes, and new substances and new markets, mainly through the internet, have appeared. Their effects and how they originate in consumers are still mostly unknown, primarily in what concerns chronic toxicity. This review intends to provide a detailed description of these substances from the point of view of consumption, toxicokinetics, and health consequences, including case reports on intoxications in order to help researchers and public health agents working daily in this area. info:eu-repo/semantics/publishedVersion

Cervical cancer (CC) is the fourth most common pathology in women worldwide and presents a high impact in developing countries due to limited financial resources as well as difficulties in monitoring and access to health services. Human papillomavirus (HPV) is the leading cause of CC, and despite the approval of prophylactic vaccines, there is no effective treatment for patients with pre-existing infections or HPV-induced carcinomas. High-risk (HR) HPV E6 and E7 oncoproteins are considered biomarkers in CC progression. Since the E6 structure was resolved, it has been one of the most studied targets to develop novel and specific therapeutics to treat/manage CC. Therefore, several small molecules (plant-derived or synthetic compounds) have been reported as blockers/inhibitors of E6 oncoprotein action, and computational-aided methods have been of high relevance in their discovery and development. In silico approaches have become a powerful tool for reducing the time and cost of the drug development process. Thus, this review will depict small molecules that are already being explored as HR HPV E6 protein blockers and in silico approaches to the design of novel therapeutics for managing CC. Besides, future perspectives in CC therapy will be briefly discussed.

This study aimed to assess alcohol consumption in a university student population though the combined analysis of the alcohol biomarkers ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEEs) in hair samples. A total of 975 hair samples were analysed for EtG and FAEEs using liquid chromatography coupled to mass spectrometry (LC–MS/MS) and gas chromatography coupled to mass spectrometry (GC–MS/MS), respectively. The results were analysed using the cut-offs proposed by the Society of Hair Testing and receiver operating characteristic (ROC) curve analysis was performed to verify the adequacy of the proposed values for the study population. Good sensitivity and specificity were obtained for both biomarkers, especially for EtG, and a correlation was found with the self-reported alcohol consumption habit. In 56.3% of the abstinent, 65.8% of the moderate and 80.0% of the excessive drinking cases, self-reported alcohol consumption could be confirmed by combined alcohol biomarker analysis. Combined analysis of EtG and FAEEs in hair samples proved to be a valuable tool for the monitoring of alcohol consumption in a student population. For a feasible result interpretation, it is very important to document the use of hair products, cosmetic treatments and washing frequency, and for these to be considered during interpretation. Overall the participants were aware of their consumption pattern, however for doubtful cases and to account for academic calendars, repeated analysis of samples collected at different time frames would be advisable.

Prostate cancer is a multifactorial disease and the second most common cancer diagnosed in men worldwide. The six transmembrane epithelial antigen of prostate (STEAP) proteins seem to be involved in prostate tumorigenesis. The STEAP proteins are differentially expressed in prostate cancer cells, and survival analysis reveal that prostate cancer patients with high levels of STEAP1 have poor survival outcomes. In contrast, high expression of STEAP4 offers a better prognosis. This chapter provides an overview of the role of STEAP proteins in prostate cancer. The structure, biological functions, and the potential prognostic significance of each of the four members of the STEAP family in prostate cancer are discussed.

Neurodegenerative diseases (ND), including Alzheimer’s (AD) and Parkinson’s Disease (PD), are becoming increasingly more common and are recognized as a social problem in modern societies. These disorders are characterized by a progressive neurodegeneration and are considered one of the main causes of disability and mortality worldwide. Currently, there is no existing cure for AD nor PD and the clinically used drugs aim only at symptomatic relief, and are not capable of stopping neurodegeneration. Over the last years, several drug candidates reached clinical trials phases, but they were suspended, mainly because of the unsatisfactory pharmacological benefits. Recently, the number of compounds developed using in silico approaches has been increasing at a promising rate, mainly evaluating the affinity for several macromolecular targets and applying filters to exclude compounds with potentially unfavorable pharmacokinetics. Thus, in this review, an overview of the current therapeutics in use for these two ND, the main targets in drug development, and the primary studies published in the last five years that used in silico approaches to design novel drug candidates for AD and PD treatment will be presented. In addition, future perspectives for the treatment of these ND will also be briefly discussed.

The Six Transmembrane Epithelial Antigen of the Prostate (STEAP1) is an oncogene overexpressed in several human tumors, particularly in prostate cancer (PCa). However, the mechanisms involved in its overexpression remain unknown. It is well known that epigenetic modifications may result in abnormal gene expression patterns, contributing to tumor initiation and progression. Therefore, this study aimed to analyze the methylation pattern of the STEAP1 gene in PCa versus non-neoplastic cells. Bisulfite amplicon sequencing of the CpG island at the STEAP1 gene promoter showed a higher methylation level in non-neoplastic PNT1A prostate cells than in human PCa samples. Bioinformatic analysis of the GEO datasets also showed the STEAP1 gene promoter as being demethylated in human PCa, and a negative association with STEAP1 mRNA expression was observed. These results are supported by the treatment of non-neoplastic PNT1A cells with DNMT and HDAC inhibitors, which induced a significant increase in STEAP1 mRNA expression. In addition, the involvement of HDAC in the regulation of STEAP1 mRNA expression was corroborated by a negative association between STEAP1 mRNA expression and HDAC4,5,7 and 9 in human PCa. In conclusion, our work indicates that STEAP1 overexpression in PCa can be driven by the hypomethylation of STEAP1 gene promoter.

Therapeutic applications of plasmid DNA (pDNA) have significantly advanced during the last years. Currently, several pDNA-based drugs are already in the market, whereas several others have entered phases 2 and 3 of clinical trials. The present and future demand for pDNA requires the development of efficient bioprocesses to produce it. Commonly, pDNA is produced by cultures of Escherichia coli. It has been previously demonstrated that specific strains of E. coli with a modified substrate transport system can be able to attain high cell densities in batch mode, due to the very low overflow metabolism displayed. However, the large amounts of oxygen demanded can lead to microaerobic conditions after some hours of cultivation, even at small scale. Typically, the inherent problems for these cultures are the high oxygen demand and the accumulation of acetate, a metabolic byproduct that is synthesized aerobically when the glucose rate exceeds the limits.In recent years, several researches have been focused on the study of induction of plasmid DNA as well as strategies for fermentation using semi-defined mediums. These studies conceived relevant results that allow us to design a production platform for enhanced plasmid DNA. So, the main goal of this chapter is to show how the development of an experimental design directed to aromatic amino acids pathway can improve the yield of a therapeutic plasmid DNA by culture of a new strain of Escherichia coli VH33.

Protein biopharmaceuticals, among which interferon alpha-2b (IFNα-2b) that can be used in the treatment of chronic hepatitis C and hairy cell leukemia, have become an indispensable product of current medicine. However, their current high costs derived from the lack of cost-effective downstream strategies still limits their widespread use. Polymer-based aqueous two-phase systems (ATPS) or aqueous biphasic systems (ABS) can be used in biopharmaceuticals purification. This work investigates the application of ionic liquids (ILs) as adjuvants (at 5 wt%) in ATPS constituted by polyethylene glycol with a molecular weight of 600 g mol−1 (PEG 600) and polypropylene glycol with a molecular weight of 400 g mol−1 (PPG 400) at constant pH (8) to purify the recombinant protein IFNα-2b from Escherichia coli lysates. IFNα-2b was produced from isopropyl β-d-1-thiogalactopyranoside (1 mM)-induced Escherichia coli BL21 (DE3) cultures and recovered from inclusion bodies after mechanical lysis, involving glass beads and a solubilization step with urea (8 M) in alkaline pH (12.5). PEG-PPG-based ATPS involving ILs as adjuvants were subsequently applied for IFNα-2b purification, in which the target protein tends to migrate to the PEG-rich phase (being the phase also enriched in IL) and the remaining proteins tend to precipitate at the interface (fitting within the three-phase partitioning approach). In comparison with the ATPS without adjuvant, most systems comprising ILs as adjuvants lead to enhancements in the purification factors of IFNα-2b, namely from 2.28 ± 0.06 up to 6.77 ± 0.49. The purity of IFNα-2b is maximized using ILs composed of aromatic cations and anions with high hydrogen-bond basicity. The secondary structure of IFNα-2b is preserved during the purification step, as appraised by circular dichroism and western-blot studies. Overall, the obtained results demonstrate the ILs ability to tune the characteristics of the ATPS coexisting phases towards improved purification processes, paving the way for their investigation in the purification of other high-value biological products.

Cancer is a global health issue that impairs the life quality of patients and origins thousands of deaths annually worldwide. Six-transmembrane epithelial antigen of the prostate (STEAP1) was identified to be overexpressed in several types of cancers, namely in prostate cancer (PCa). Considering its secondary structure, associated with its location in the cell membrane, has been suggested a role in intercellular communication between tumour cells. Taking into account its high specificity and overexpression in human cancers, STEAP1 is nowadays a promising candidate to be imposed as a therapeutic target. Several strategies have been developed during the last few years for targeting STEAP1, including antibody-drug conjugates, monoclonal antibodies (mAbs), DNA vaccines and small noncoding RNAs (ncRNAs). This review presents the current knowledge about STEAP1 protein expression in human tissues, its biochemical properties and targeting strategies with the purpose to evaluate its potential as therapeutic agent for cancer.

Catechol-O-methyltransferase (COMT) is an enzyme involved in catecholamine catabolism that is key for the treatment of different neurologic disorders. Actually, there are still unmet needs concerning the development of more selective membrane-bound COMT (hMBCOMT) downstream strategies, envisaging their application in structural and bio-interaction studies. Therefore, in this work, recombinant hexahistidine-tagged hMBCOMT (hMBCOMT-His6) was expressed from Pichia pastoris methanol-induced cultures in a catalytically active form (27.3 nmol h−1 mg−1 of protein) and successfully solubilized with n-dodecyl β-d-maltoside. Afterward, immobilized-metal affinity chromatography provided the required selectivity for the direct capture of hMBCOMT-His6 from detergent-solubilized P. pastoris membranes, being the target enzyme recovered in a highly purified fraction. Also, despite the relatively low purification fold (1.53), the purity of the target enzyme assessed by SDS-PAGE is high and it is recovered with biological activity (67 nmol h−1 mg−1 of protein). Then, after a final polishing stage using Q-Sepharose, a pure and immunologically active enzyme fraction was obtained. Overall, the strategy herein reported may be applied to obtain pure hMBCOMT fractions, debottlenecking the implementation of bio-interaction studies and relieving the problems associated with hMBCOMT drug discovery pipeline. In a last analysis, these studies may lead to the establishment of new pharmacological therapies, thereby improving the prognosis of neurologic disorders.

This work explores the application of divalent cations-crosslinked gellan microspheres to capture pDNA from a complex Escherichia coli lysate through the batch method. Copper-crosslinked gellan microspheres allowed 15.61% of pDNA recovery with 2.42% of purity, through a strategy based on immobilized metal affinity chromatography, by manipulating the pH and ionic strength. Another strategy was developed, including a previous clarification step with ammonium sulfate, which improved the recovery percentage to 32.41%, and the purity degree to 12.43%. Moreover, copper-crosslinked gellan microspheres were functionalized with polyethylenimine ligands, which resulted into a significant improvement of pDNA capture (88.09% of recovery yield), although the purity has been 3.18%. Considering that E. coli lysate initially has 1.07% pDNA, these simple strategies allow the pDNA capture and lysate clarification to be directly applied in a purification process without the need of organic solvents, reducing the environmental impact for pharmaceutical industry.

Funding Information: Acknowledgments: The authors acknowledge the support from FEDER funds through the POCI‐ COMPETE 2020–Operational Programme Competitiveness and Internationalisation in Axis I– Strengthening research, technological development and innovation (Project POCI‐01‐0145‐FEDER‐ 007491) and National Funds (Project UID/Multi/00709/2013), Jorge Barroca‐Ferreira’s and Sandra Rocha’s individual PhD Fellowship (SFRH/BD/130068/2017 and SFRH/BD/115693/2016, respectively), and Luís A. Passarinha’s sabbatical fellowship (SFRH/BSAB/150376/2019) from FCT– Fundação para a Ciência e Tecnologia. This work was also supported by the Applied Molecular Biosciences Unit UCIBIO (UIDB/04378/2020 and UIDP/04378/2020) and the Associate Laboratory Institute for Health and Bioeconomy–i4HB (project LA/P/0140/2020) which are financed by National Funds from FCT/MCTES. Funding Information: The authors acknowledge the support from FEDER funds through the POCI- COMPETE 2020?Operational Programme Competitiveness and Internationalisation in Axis I? Strengthening research, technological development and innovation (Project POCI-01-0145-FEDER- 007491) and National Funds (Project UID/Multi/00709/2013), Jorge Barroca-Ferreira?s and Sandra Rocha?s individual PhD Fellowship (SFRH/BD/130068/2017 and SFRH/BD/115693/2016, respectively), and Lu?s A. Passarinha?s sabbatical fellowship (SFRH/BSAB/150376/2019) from FCT? Funda??o para a Ci?ncia e Tecnologia. This work was also supported by the Applied Molecular Biosciences Unit UCIBIO (UIDB/04378/2020 and UIDP/04378/2020) and the Associate Laboratory Institute for Health and Bioeconomy?i4HB (project LA/P/0140/2020) which are financed by National Funds from FCT/MCTES. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Background: The STEAP1 is a cell-surface antigen over-expressed in prostate cancer, which contributes to tumor progression and aggressiveness. However, the molecular mechanisms underlying STEAP1 and its structural determinants remain elusive. Methods: The fraction capacity of Butyl- and Octyl-Sepharose matrices on LNCaP lysates was evaluated by manipulating the ionic strength of binding and elution phases, followed by a Co-Immunoprecipitation (Co-IP) polishing. Several potential stabilizing additives were assessed, and the melting temperature (Tm) values ranked the best/worst compounds. The secondary structure of STEAP1 was identified by circular dichroism. Results: The STEAP1 was not fully captured with 1.375 M (Butyl), in contrast with interfering heterologous proteins, which were strongly retained and mostly eluted with water. This single step demonstrated higher selectivity of Butyl-Sepharose for host impurities removal from injected crude samples. Co-IP allowed recovering a purified fraction of STEAP1 and contributed to unveil potential physiologically interacting counterparts with the target. A Tm of ~55 °C was determined, confirming STEAP1 stability in the purification buffer. A predominant α-helical structure was identified, ensuring the protein’s structural stability. Conclusions: A method for successfully isolating human STEAP1 from LNCaP cells was provided, avoiding the use of detergents to achieve stability, even outside a membrane-mimicking environment. publishersversion published

Membrane proteins (MP) constitute 20–30% of all proteins encoded by the genome of various organisms and perform a wide range of essential biological functions. However, despite they represent the largest class of protein drug targets, a relatively small number high-resolution 3D structures have been obtained yet. Membrane protein biogenesis is more complex than that of the soluble proteins and its recombinant biosynthesis has been a major drawback, thus delaying their further structural characterization. Indeed, the major limitation in structure determination of MP is the low yield achieved in recombinant expression, usually coupled to low functionality, pinpointing the optimization target in recombinant MP research. Recently, the growing attention that have been dedicated to the upstream stage of MP bioprocesses allowed great advances, permitting the evolution of the number of MP solved structures. In this review, we analyse and discuss effective solutions and technical advances at the level of the upstream stage using prokaryotic and eukaryotic organisms foreseeing an increase in expression yields of correctly folded MP and that may facilitate the determination of their three-dimensional structure. A section on techniques used to protein quality control and further structure determination of MP is also included. Lastly, a critical assessment of major factors contributing for a good decision-making process related to the upstream stage of MP is presented. Electronic supplementary material The online version of this article (10.1007/s00253-019-09873-1) contains supplementary material, which is available to authorized users.

In the present work, the biosynthesis of the gellan gum exopolysaccharide from Sphingomonas paucimobilis fermentation was improved to 24 g/L, by increasing the oxygen content (1:5). FTIR and NMR data indicated the following procedures to recover gellan from culture medium: filtration; washing with acetone and ether (200 mL each one); permeate dissolution with distilled water; precipitation with acetonitrile (1:3). Gellan microsphere formulation by water-in-oil emulsion was optimized through central composite design to minimize the diameter (≈ 300 μm), and reinforced with different counter-ions. The optimal point was reached with 1.27% gellan concentration, 750 rpm and 92.54 °C of oil temperature. Microspheres with nickel as counter-ion revealed the most satisfactory results from semi-optical microscopy, SEM and EDX analysis. The manipulation of ionic strength or pH on the binding and elution steps allowed capturing different model proteins, exploring electrostatic or affinity interactions with these microspheres.

Despite technological advances, two-dimensional electrophoresis (2DE) of biological fluids, such as vitreous, remains a major challenge. In this study, artificial neural network was applied to optimize the recovery of vitreous proteins and its detection by 2DE analysis through the combination of several solubilizing agents (CHAPS, Genapol, DTT, IPG buffer), temperature, and total voltage. The highest protein recovery (94.9% ± 4.5) was achieved using 4% (w/v) CHAPS, 0.1% (v/v) Genapol, 20 mM DTT, and 2% (v/v) IPG buffer. Two iterations were required to achieve an optimized response (580 spots) using 4% (w/v) CHAPS, 0.2% (v/v) Genapol, 60 mM DTT, and 0.5% (v/v) IPG buffer at 35 kVh and 25 °C, representing a 2.4-fold improvement over the standard initial conditions of the experimental design. The analysis of depleted vitreous using the optimized protocol resulted in an additional 1.3-fold increment in protein detection over the optimal output, with an average of 761 spots detected in vitreous from different vitreoretinopathies. Our results clearly indicate the importance of combining the appropriate amount of solubilizing agents with a suitable control of the temperature and voltage to obtain high-quality gels. The high-throughput of this model provides an effective starting point for the optimization of 2DE protocols. This experimental design can be adapted to other types of matrices. Graphical abstract., CENTRO-07-ST24-FEDER-002014; CNB-CSIC is supported by grant PT13/0001, of the PE I +D+i 2013–2016, funded by ISCIII and FEDER.

Environmental tobacco smoke exposure (ETS) and smoking have been described as the most prevalent factors in the development of certain diseases worldwide. According to the World Health Organization, more than 8 million people die every year due to exposure to tobacco, around 7 million due to direct ETS and the remaining due to exposure to second-hand smoke. Both active and second-hand exposure can be measured and controlled using specific biomarkers of tobacco and its derivatives, allowing the development of more efficient public health policies. Exposure to these compounds can be measured using different methods (involving for instance liquid- or gas-chromatographic procedures) in a wide range of biological specimens to estimate the type and degree of tobacco exposure. In recent years, a lot of research has been carried out using different extraction methods and different analytical equipment; this way, liquid–liquid extraction, solid-phase extraction or even miniaturized procedures have been used, followed by chromatographic analysis coupled mainly to mass spectrometric detection. Through this type of methodologies, second-hand smokers can be distinguished from active smokers, and this is also valid for e-cigarettes and vapers, among others, using their specific biomarkers. This review will focus on recent developments in the determination of tobacco smoke biomarkers, including nicotine and other tobacco alkaloids, specific nitrosamines, polycyclic aromatic hydrocarbons, etc. The methods for their detection will be discussed in detail, as well as the potential use of threshold values to distinguish between types of exposure.

BACKGROUND Catechol-O-methyltransferase (COMT, EC 2.1.1.6) has been implicated in several human diseases including Parkinson's disease and the most appropriated therapy depends on the efficacy of the COMT inhibitors applied. Therefore, more effective drugs for COMT inhibition are important, and the development of such inhibitors requires research with recombinant COMT. RESULTS The time-course production of biologically active hexa-histidine-tagged COMT in methanol-induced Pichia pastoris cultures was evaluated and immobilized-metal affinity chromatography was applied as the main capture step for the purification of the target enzyme that proved to be extremely efficient and selective. The best strategy allowed recovering soluble COMT at 300 mmol L−1 imidazol in a highly purified fraction with a purification fold of 81 and a bioactivity recovery of 57.35%. Using this strategy, a concentration of 3.68 mg L−1 of shake-flask culture of highly purified recombinant COMT was obtained. Finally, the MALDI-TOF/TOF analysis of the purified recombinant SCOMT demonstrated that it is correctly processed since no modifications in the primary sequence were observed. CONCLUSION A new strategy was developed and implemented for the biosynthesis and purification of biologically active soluble COMT in a highly purified fraction with the ability to be inhibited by commercial Parkinson's disease inhibitors: 3,5-dinitrocatechol and entacapone. © 2016 Society of Chemical Industry

VEGF-A and VEGF-B are proangiogenic and key regulating factors for blood vessel growth. This study aims to compare VEGF-A and VEGF-B levels in the serum and vitreous of patients with neovascular pathology versus non-neovascular pathology. Our findings showed vitreous VEGF-A and VEGF-B levels increased in patients with neovascular disease, with higher levels of VEGF-A compared to VEGF-B (p ≤ .05). In the diabetic retinopathy (DR) group, higher vitreous VEGF-A or VEGF-B were found in proliferative diabetic retinopathy (PDR) than in non-PDR. The strong correlation between VEGF-A and VEGF-B demonstrates a simultaneous pathological increase of cytokines (p, POCI-01-0145-FEDER-007491

Rhegmatogenous retinal detachment (RRD) is a potentially blinding condition characterized by a physical separation between neurosensory retina and retinal pigment epithelium. Quantitative proteomics can help to understand the changes that occur at the cellular level during RRD, providing additional information about the molecular mechanisms underlying its pathogenesis. In the present study, iTRAQ labeling was combined with two-dimensional LC-ESI-MS/MS to find expression changes in the proteome of vitreous from patients with RRD when compared to control samples. A total of 150 proteins were found differentially expressed in the vitreous of patients with RRD, including 96 overexpressed and 54 underexpressed. Several overexpressed proteins, several such as glycolytic enzymes (fructose-bisphosphate aldolase A, gamma-enolase, and phosphoglycerate kinase 1), glucose transporters (GLUT-1), growth factors (metalloproteinase inhibitor 1), and serine protease inhibitors (plasminogen activator inhibitor 1) are regulated by HIF-1, which suggests that HIF-1 signaling pathway can be triggered in response to RRD. Also, the accumulation of photoreceptor proteins, including phosducin, rhodopsin, and s-arrestin, and vimentin in vitreous may indicate that photoreceptor degeneration occurs in RRD. Also, the accumulation of photoreceptor proteins, including phosducin, rhodopsin, and s-arrestin, and vimentin in vitreous may indicate that photoreceptor degeneration occurs in RRD. Nevertheless, the differentially expressed proteins found in this study suggest that different mechanisms are activated after RRD to promote the survival of retinal cells through complex cellular responses., CENTRO-07-ST24-FEDER-002014; POCI-01-0145-FEDER-007491; CNB-CSIC proteomics lab is a member of ProteoRed, supported by PRB2-ISCIII grant [PT13/0001]; Novartis Farma-Produtos Farmacêuticos; PhD fellowship of Sciences Faculty financed by ICI and Santander.

The cerebrospinal fluid melatonin is released from the pineal gland, directly into the third ventricle, or produced de novo in the brain from extrapineal melatonin sources leading to a melatonin concentration gradient in the cerebrospinal fluid. Despite the interest on this topic, the brain areas capable of producing melatonin are not yet clear. Bearing this in mind, we hypothesized that the choroid plexus (CP) could be one of these melatonin sources. We analyzed and confirmed the presence of the four enzymes required for melatonin synthesis in rat CP and demonstrated that arylalkylamine N-acetyltransferase shows a circadian expression in female and male rat CP. Specifically, this enzyme colocalizes with mitochondria in rat CP epithelial cells, an organelle known to be involved in melatonin function and synthesis. Then, we demonstrated that melatonin is synthesized by porcine CP explants, although without a circadian pattern. In conclusion, our data show that the CP is a local source of melatonin to the central nervous system, probably contributing to its high levels in the cerebrospinal fluid. We believe that in the CP, melatonin might be regulated by its endogenous clock machinery and by the hormonal background.

Affinity chromatography strategies using amino acids as immobilize d ligands have been successfully applied for the purification of different biomolecules from complex mixtures. Therefore, in this work, several supports with immobilized amino acids were applied for the purification of membrane-bound catechol-O-methyltransferase (MBCOMT) from Pichia pastoris lysates and it was verified that l-arginine provided the required selectivity for MBCOMT isolation. The optimization of the binding and elution buffers composition allowed the recovery of purified MBCOMT in a biological and immunologically active state from the arginine support. Additional optimization experiments varying the mobile phase pH, temperature and the concentration of the injected sample were carried out and an improvement of MBCOMT adsorption and purity was observed. Indeed, the optimized conditions for MBCOMT isolation and purification consisted in: loading of 4 mg of total protein onto the column previously equilibrated at 20 °C where the target enzyme was recovered in a purified fraction using 500 mM NaCl, 10 mM DTT and 0.5 % (v/v) Triton X-100 in 10 mM Tris buffer (pH 7) with a total bioactivity recovery of 24 ± 2.2 % and a purification fold of 4.95 ± 0.23, a value that is consistent with the best values ever reported for MBCOMT. Moreover, the l-arginine support demonstrated the ability to bind the target protein in a wide range of pH values (above and below the pI of the target protein) and the MBCOMT elution occurs in a single peak pattern. Finally, the strategy here reported can aid in the implementation of crystallization studies with MBCOMT in complex with clinically relevant inhibitors since it is obtained in a purified form with biological activity. In conclusion, a novel affinity chromatography strategy was developed and implemented for recombinant MBCOMT purification in a highly immunological and biologically active state.

Therapeutic applications of plasmid DNA have significantly advanced during the last years and future demand for plasmid DNA requires the development of efficient bioprocesses. Concerning these facts, our aim is to optimize the yield of a therapeutic plasmid pcDNA3–FLAG–p53 using a new bacterial strain, Escherichia coli VH33. This innovative research combines the potential of VH33, which uses a different glucose transport allowing efficient growth and lower acetate production, for pDNA biosynthesis with a validated factorial design. This work achieved higher plasmid yields of 81.77 μg pDNA/mL, when compared with other results for similar assays which reached about 40 μg pDNA/mL. The strategy is based on the change of fermentation media composition in terms of nutrients, by the development of an experimental design directed to aromatic amino acids pathway. The results revealed which combination should be applied in terms of nitrogen and carbon source requirements in order to obtain 36.69 μg pDNA/mg cell dry mass of specific yields and 6.01% of purity on lysates. Overall, the proposal model show the influence of tyrosine, phenylalanine and tryptophan on their pathway, providing necessary precursors to nucleotides’ network, as well as temperature shift (37–42 °C) to increase the plasmid copy number per cell.

Catechol-O-methyltransferase (COMT, EC 2.1.1.6) is an enzyme that catalyzes the methylation of catechol substrates, and while structural and functional studies of its membrane-bound isoform (MBCOMT) are still hampered by low recombinant production, Pichia pastoris has been described as an attractive host for the production of correctly folded and inserted membrane proteins. Hence, in this work, MBCOMT biosynthesis was developed using P. pastoris X33 and KM71H cells in shake flasks containing a semidefined medium with different methanol concentrations. Moreover, after P. pastoris glass beads lysis, biologically and immunologically active hMBCOMT was found mainly in the solubilized membrane fraction whose kinetic parameters were identical to its correspondent native enzyme. In addition, mixed feeds of methanol and glycerol or sorbitol were also employed, and its levels quantified using liquid chromatography coupled to refractive index detection. Overall, for the first time, two P. pastoris strains with opposite phenotypes were applied for MBCOMT biosynthesis under the control of the strongly methanol-inducible alcohol oxidase (AOX) promoter. Moreover, this eukaryotic system seems to be a promising approach to deliver MBCOMT in high quantities from fermentor cultures with a lower cost-benefit due to the cheaper cultivation media coupled with the higher titers tipically achieved in biorreactors, when compared with previously reported mammallian cell cultures., A.Q. Pedro acknowledges a doctoral fellowship (SFRH/BD/81222/2011) from Fundação para a Ciência e Tecnologia and D. Oppolzer acknowledges a fellowship (CENTRO-07-ST24_FEDER-002014- TPCR-2-004) from Programa BMais Centro^ within the scope of QREN–POPH–Advanced Formation programs cofunded by Fundo Social Europeu and MEC. This work was partially funded by Fundação para a Ciência e Tecnologia I.P. (PIDDAC) and Fundo Europeu de Desenvolvimento Regional-FEDER funds through Programa Operacional Factores de Competitividade (POFC)–COMPETE: FCOMP-01-0124-FEDER-027563 and by National Funds through FCT–Fundação para a Ciência e Tecnologia within the scope of Project BEXPL/BBB478/ BQB/0960/2012.

The vitreous humor (VH) is the largest component of the eye. It is a colorless, gelatinous, highly hydrated matrix that fills the posterior segment of the eye between the lens and retina in vertebrates. In VH, a diversity of proteins that can influence retinal physiology is present, including growth factors, hormones, proteins with transporter activity, and enzymes. More importantly, the protein composition of VH has been described as being altered in a number of disease states. Therefore, attempts aiming at establishing a map of VH proteins and detecting putative biomarkers for ocular illness or protein fluctuations with putative physiologic significance were conducted over the last two decades, using proteomic approaches. Proteomic strategies often involve gel-based or LC techniques as sample fractioning approaches, subsequently coupled with MS procedures. This set of studies resulted in the proteomic characterization of a range of ocular disease samples, with particular incidence on diabetic retinopathy. However, practical therapeutic applications arising from these studies are scarce at the moment. A pertinent example of therapeutic targets arising from VH proteomics has emerged concerning vasoproliferative factors present in the vitreous, which should be involved in neovascularization and subsequent fibrovascular proliferation of the retina, in ocular disease context. Therefore, this review attempts to sum up the information acquired from the proteomic approaches to ocular disease conducted in VH samples, highlighting its clinical potential for disclosing ocular disease mechanisms and engendering pharmacological therapeutic treatments.

Nisin is a natural peptide used as a preservative in a variety of food products, in which it inhibits mainly Gram-positive bacterial growth, including multidrug-resistant pathogens. However, its application range depends on the cost-effective production and purification of this molecule. Our group has previously produced nisin by Lactococcus lactis cultivation in milk whey, which is an industrial residue from dairy production. To our knowledge, no report used milk whey as a culture medium, although several investigators have purified nisin using different techniques. We thus aimed to establish a low-cost purification of nisin obtained by this process. Samples were diluted in ammonium sulphate, applied onto \HIC\ columns (butyl sepharose \CL\ 4B matrix), and eluted with Milli-Q water or PBS. Elution fractions were monitored for protein content and nisin antibacterial activity. Water elution resulted in purification factor values (270, commercial nisin; 775, nisin produced in-house) higher than those obtained with \PBS\ elution. We concluded that purification of nisin does not require precipitation with ammonium sulphate, therefore allowing step/cost reduction. Moreover, purification from milk whey using \HIC\ provides nisin with high activity and low salt content, which can further be applied to a variety of areas., This study was supported by grants from CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior, Brazil), CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Brazil) and FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, Brazil). We thank Dr. Paulo Boschcov for his careful and critical reading of our final manuscript.