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A series of eight gold(I) N-heterocyclic carbene (NHC) complexes [Au(IMes)(Ln)] based on 1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene (IMes) and 7-azaindole derivatives (HLn), where n = 1-8 for HL1 = 5-fluoro-7-azaindole, HL2 = 5-bromo-7-azaindole, HL3 = 3-chloro-7-azaindole, HL4 = 3-iodo-7-azaindole, HL5 = 5-bromo-3-chloro-7-azaindole, HL6 = 5-bromo-3-iodo-7-azaindole, HL7 = 4-chloro-2-methyl-7-azaindole and HL8 = 7-azaindole, was prepared, characterised and studied for their in vitro anti-cancer and anti-inflammatory effects. The complexes showed significant cytotoxicity on human ovarian cancer cell lines (A2780, IC 50  ≈ 8-19 μM and A2780R, IC 50  ≈ 8-19 μM) and lowered toxicity in normal HaCat and MRC-5 cells. Cellular effects of the selected complexes 1 and 7 were evaluated in A2780 cells using flow cytometry. Moreover, the time-dependent cellular uptake in A2780 cells, a shotgun proteomic analysis, an ESI-MS study of hydrolysis and interactions with l-cysteine and reduced glutathione (GSH) were performed. Complexes 1 and 7 revealed remarkable anti-inflammatory effects via inhibition of NF-κB activity in human endothelial cells., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Zdeněk Trávníček reports financial support was provided by the Czech Science Foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

Over the past decades, the proteomics field has undergone rapid growth. Progress in mass spectrometry and bioinformatics, together with separation methods, has brought many innovative approaches to the study of the molecular biology of the cell. The potential of affinity chromatography was recognized immediately after its first application in proteomics, and since that time, it has become one of the cornerstones of many proteomic protocols. Indeed, this chromatographic technique exploiting the specific binding between two molecules has been employed for numerous purposes, from selective removal of interfering (over)abundant proteins or enrichment of scarce biomarkers in complex biological samples to mapping the post-translational modifications and protein interactions with other proteins, nucleic acids or biologically active small molecules. This review presents a comprehensive survey of this versatile analytical tool in current proteomics. To navigate the reader, the haphazard space of affinity separations is classified according to the experiment's aims and the separated molecule's nature. Different types of available ligands and experimental strategies are discussed in further detail for each of the mentioned procedures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Apidaecins represent an important group of antimicrobial peptides occurring in honey bee hemolymph, where they play an important role as key components of humoral immunity. The present study demonstrates the development of a highly sensitive assay for apidaecin 1 isoforms quantification in the hemolymph or body parts from honey bee individuals. The analytical protocol comprises apidaecins 1 purification and enrichment steps by weak cation-exchange chromatography (WCX) in laboratory-made WCX-Tip microcolumns combined with a desalting step on a reversed-phase sorbent (C8) carried in StageTips. Apidaecin-enriched fraction was analyzed by a reversed-phase based nanoliquid chromatography (C4) separation coupled with high-resolution mass spectrometry. The method performance was validated in its specificity, linearity (0-5pmol), recovery (∼45%), precision (<10% at 0.1pmol), limit of detection (∼50fmol), limit of quantification (0.1pmol) and sample stability. The method was successfully applied to analyze the content of apidaecin 1 isoforms in the following samples: hemolymph - 13.0ng/μL (95% confidence interval of 7.5-18.6ng/μL), thoraxes - 36.2ng/unit (95% CI of 18.9-53.6ng/unit) and heads - 12.9ng/unit (95% CI of 9.1-16.7ng/unit). Freshly emerged bees had apidaecin 1 isoforms levels below the limit of detection. Thus it was possible to use them as a competitive matrix for calibration standards to prevent losses of highly basic apidaecins. This new protocol for apidaecin 1 isoforms quantification represents a promising tool to study the role of apidaecins in honey bee immunity and can be considered as a proof-of-concept for the development of sensitive quantification methods for basic antimicrobial peptides in various organisms., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Cytokinin oxidase/dehydrogenase (CKO; EC 1.5.99.12) irreversibly degrades the plant hormones cytokinins. A recombinant maize isoenzyme 1 (ZmCKO1) produced in the yeast Yarrowia lipolytica was subjected to enzymatic deglycosylation by endoglycosidase H. Spectrophotometric assays showed that both activity and thermostability of the enzyme decreased after the treatment at non-denaturing conditions indicating the biological importance of ZmCKO1 glycosylation. The released N-glycans were purified with graphitized carbon sorbent and analyzed by MALDI-TOF MS. The structure of the measured high-mannose type N-glycans was confirmed by tandem mass spectrometry (MS/MS) on a Q-TOF instrument with electrospray ionization. Further experiments were focused on direct analysis of sugar binding. Peptides and glycopeptides purified from tryptic digests of recombinant ZmCKO1 were separated by reversed-phase chromatography using a manual microgradient device; the latter were then subjected to offline-coupled analysis on a MALDI-TOF/TOF instrument. Glycopeptide sequencing by MALDI-TOF/TOF MS/MS demonstrated N-glycosylation at Asn52, 63, 134, 294, 323 and 338. The bound glycans contained 3-14 mannose residues. Interestingly, Asn134 was found only partially glycosylated. Asn338 was the sole site to carry large glycan chains exceeding 25 mannose residues. This observation demonstrates that contrary to a previous belief, the heterologous expression in Y. lipolytica may lead to locally hyperglycosylated proteins., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The use of trypsin for protein digestion is hampered by its autolysis and low thermostability. Chemical modifications have been employed to stabilize the enzyme. Modified trypsin (e.g. methylated) usually enables performing digestions at elevated temperatures, but it still produces autolytic peptides. In this work, unmodified bovine trypsin was subjected to a microscale affinity chromatography on Arginine Sepharose (ASE) or Benzamidine Sepharose (BSE), which utilized the principle of active-site ligand binding. Trypsin was retained on the sorbents in ammonium bicarbonate as a binding buffer. After washings to remove unbound impurities, the enzyme was eluted by arginine as a free ligand (from ASE) or by diluted hydrochloric acid (from BSE). MALDI-TOF mass spectrometry confirmed removal of large molecular fragments as well as autolytic and other background peptides. Consequently, the purified trypsin was tested for its performance in procedures of in-gel digestion of protein standards and selected urinary proteins from real samples. It has been shown that the affinity purification of trypsin decreases significantly the number of unmatched peptides in peptide mass fingerprints. The presence of arginine in the digestion buffer was found to reduce intensity of autolytic peptides. As a result, the described purification procedure is applicable in a common proteomic routine., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Cytokinin ribosides (N(6)-substituted adenosine derivatives) have been shown to have anticancer activity both in vitro and in vivo. This study presents the first systematic analysis of the relationship between the chemical structure of cytokinins and their cytotoxic effects against a panel of human cancer cell lines with diverse histopathological origins. The results confirm the cytotoxic activity of N(6)-isopentenyladenosine, kinetin riboside, and N(6)-benzyladenosine and show that the spectrum of cell lines that are sensitive to these compounds and their tissues of origin are wider than previously reported. The first evidence that the hydroxylated aromatic cytokinins (ortho-, meta-, para-topolin riboside) and the isoprenoid cytokinin cis-zeatin riboside have cytotoxic activities is presented. Most cell lines in the panel showed greatest sensitivity to ortho-topolin riboside (IC(50)=0.5-11.6 microM). Cytokinin nucleotides, some synthesized for the first time in this study, were usually active in a similar concentration range to the corresponding ribosides. However, cytokinin free bases, 2-methylthio derivatives and both O- and N-glucosides showed little or no toxicity. Overall the study shows that structural requirements for cytotoxic activity of cytokinins against human cancer cell lines differ from the requirements for their activity in plant bioassays. The potent anticancer activity of ortho-topolin riboside (GI(50)=0.07-84.60 microM, 1st quartile=0.33 microM, median=0.65 microM, 3rd quartile=1.94 microM) was confirmed using NCI(60), a standard panel of 59 cell lines, originating from nine different tissues. Further, the activity pattern of oTR was distinctly different from those of standard anticancer drugs, suggesting that it has a unique mechanism of activity. In comparison with standard drugs, oTR showed exceptional cytotoxic activity against NCI(60) cell lines with a mutated p53 tumour suppressor gene. oTR also exhibited significant anticancer activity against several tumour models in in vivo hollow fibre assays., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Aminoaldehyde dehydrogenases (AMADHs, EC 1.2.1.19) belong to the large aldehyde dehydrogenase (ALDH) superfamily, namely, the ALDH9 family. They oxidize polyamine-derived omega-aminoaldehydes to the corresponding omega-amino acids. Here, we report the first X-ray structures of plant AMADHs: two isoenzymes, PsAMADH1 and PsAMADH2, from Pisum sativum in complex with beta-nicotinamide adenine dinucleotide (NAD(+)) at 2.4 and 2.15 A resolution, respectively. Both recombinant proteins are dimeric and, similarly to other ALDHs, each monomer is composed of an oligomerization domain, a coenzyme binding domain and a catalytic domain. Each subunit binds NAD(+) as a coenzyme, contains a solvent-accessible C-terminal peroxisomal targeting signal (type 1) and a cation bound in the cavity close to the NAD(+) binding site. While the NAD(+) binding mode is classical for PsAMADH2, that for PsAMADH1 is unusual among ALDHs. A glycerol molecule occupies the substrate binding site and mimics a bound substrate. Structural analysis and substrate specificity study of both isoenzymes in combination with data published previously on other ALDH9 family members show that the established categorization of such enzymes into distinct groups based on substrate specificity is no more appropriate, because many of them seem capable of oxidizing a large spectrum of aminoaldehyde substrates. PsAMADH1 and PsAMADH2 can oxidize N,N,N-trimethyl-4-aminobutyraldehyde into gamma-butyrobetaine, which is the carnitine precursor in animal cells. This activity highly suggests that in addition to their contribution to the formation of compatible osmolytes such as glycine betaine, beta-alanine betaine and gamma-aminobutyric acid, AMADHs might participate in carnitine biosynthesis in plants., ((c) 2009 Elsevier Ltd. All rights reserved.)

A range of benzylaminopurines naturally occur in plants and exhibit high biological activity. Others have been synthesized, such as 6-(2-hydroxy-3-methoxybenzylamino)purine riboside (2OH3MeOBAPR), which has shown interesting anti-cancer activity under in vitro conditions. In order to study the biological activity of this interesting compound in more detail, a rapid and highly efficient method for its purification from complex samples (e.g. blood and plant extracts) is needed. Therefore, we prepared monoclonal antibodies against 2OH3MeOBAPR. The antibody had undetectable cross-reactivity with all natural isoprenoid cytokinins, but relatively high cross-reactivity with aromatic cytokinins as well as some synthetic di- and tri-substituted 6-benzylaminopurines and the corresponding ribosides. The antibody also showed strong responses and specificity in enzyme-linked immunoassays (ELISAs). In addition, it was used to prepare, for the first time, an immunoaffinity sorbent with high specificity and capacity for aromatic cytokinins. A batch immunoextraction method was then developed and optimized for the purification of 2OH3MeOBAPR from murine blood samples. The high efficacy and simplicity of this method (in off-line combination with HPLC-MS) for the isolation of target analytes from biological material is demonstrated in this study.

A single-step, highly specific and easy-to-use method was developed for isolation and purification of melatonin from complex biological matrices. Polyclonal antibodies highly specific against melatonin (with cross-reactivities with related compounds below 0.02%, except for 6-hydroxymelatonin) were raised, characterised by enzyme-linked immunosorbent assay (ELISA) and used for preparation of immunoaffinity gel. Melatonin recovery by the immunoaffinity method was approximately 95%, allowing single-step processing of samples prior to electrospray HPLC-MS analysis (with detection limit 10 fmol). The method was successfully used for determining melatonin in human serum and turned out to be better than the non-specific solid-phase extraction published earlier., (Copyright 2002 Elsevier Science BV.)