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Objective: To investigate whether murine peroxidase reductase-5 (mPRDX5) has anti-tumor activity in mice, so as to further confirm the anti-tumor activity and mechanism of recombinant peroxidase reductase-5. Methods: High purity mPRDX5 was obtained by heterologous expression and purification in vitro. Pancreatic cancer Pan02 cells were inoculated subcutaneously on the left axillary back of mice to establish a tumor bearing mouse model. Mice were randomly divided into PBS (solvent control) group, GEM (gemcitabine) 50.0 mg/kg group and mPRDX5 10.0 mg/kg group, with 10 mice in each group, and the tumor related indexes were detected in mice. Results: Compared with PBS group, weight of tumor-bearing mice in GEM group was decreased obviously, while weight of mPRDX5 group was increased to a certain extent. Tumor growth was good in PBS group, according to tumor volume, compared with PBS group, tumor growth inhibition rates in D7 were 87.07% in GEM group and 52.82% in mPRDX5 10.0 mg/kg group, respectively ; according to tumor weight, compared with PBS group, GEM group and mPRDX5 10.0 mg/kg group had tumor growth inhibition rates of 95.39% and 48.33% in D7, respectively. Polarization state of macrophages in tumor tissues of mice in PBS group and mPRDX5 group was analyzed, and it was found that compared with PBS group, M1 macrophages expressing CD86 in tumor tissues of mice in mPRDX5 group were significantly increased, while M2 macrophages expressing CD206 were significantly decreased. Conclusion: mPRDX5 has significant anti-pancreatic cancer activity in mice, and the activity is exerted by promoting M1 -type polarization of macrophages in the tumor microenvironment. [ABSTRACT FROM AUTHOR]

• The reaction mechanism of the asymmetric passerini reaction catalyzed by chiral phosphoric acid (CP6) was theoretically investigated. • The effect of weak interactions on the enantioselectivity of the reaction was revealed. • The activation mechanism of CP6 in the reaction was elucidated. The enantioselective control of the three-component Passerini reaction was successfully achieved using chiral phosphoric acid as a catalyst with a wide range of substrates and high stereoselectivity. Quantum mechanical calculations reveals the detailed reaction mechanism and enantioselective origin of the reaction. The calculations revealed that the chiral phosphoric acid first forms a stable heterodimer with the carboxylic acid substrate, followed by C- C and C- O bond formations, the generation of a five-membered cyclic intermediate, and finally acyl migration to yield the product. Four reaction paths for the overall process were identified and compared to determine the optimal major and by-product paths. The enantioselective origin of the reaction has been elucidated systematically using distortion/interaction theory and truncated model system. QTAIM and IGMH analyses demonstrated the type and strength of interaction between catalyst and the substrates. The calculated e.e. value was 93 %, which was in good agreement with the experimental value. It is expected that the results of this study will offer new insights into the field of asymmetric Passerini reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

Phenylalanine ammonia-lyase (PAL) has various applications in fine chemical manufacturing and the pharmaceutical industry. In particular, PAL derived from Anabaena variabilis (AvPAL) is used as a therapeutic agent to the treat phenylketonuria in clinical settings. In this study, we aligned the amino acid sequences of AvPAL and PAL derived from Nostoc punctiforme (NpPAL) to obtain several mutants with enhanced activity, expression yield, and thermal stability via amino acid substitution and saturation mutagenesis at the N -terminal position. Enzyme kinetic experiments revealed that the k cat values of NpPAL-N2K, NpPAL-I3T, and NpPAL-T4L mutants were increased to 3.2-, 2.8-, and 3.3-fold that of the wild-type, respectively. Saturation mutagenesis of the fourth amino acid in AvPAL revealed that the k cat values of AvPAL-L4N, AvPAL-L4P, AvPAL-L4Q and AvPAL-L4S increased to 4.0-, 3.7-, 3.6-, and 3.2-fold, respectively. Additionally, the soluble protein yield of AvPAL-L4K increased to approximately 14 mg/L, which is approximately 3.5-fold that of AvPAL. Molecular dynamics studies further revealed that maintaining the attacking state of the reaction and N -terminal structure increased the rate of catalytic reaction and improved the solubility of proteins. These findings provide new insights for the rational design of PAL in the future. [ABSTRACT FROM AUTHOR]

First principles investigation and Hirshfeld surface analysis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystals have been carried out. The geometrical and electronic structures of TATB molecules in the crystal and gas phases were compared. The Hirshfeld surface analysis of the TATB crystal structure shows that the intermolecular H⋯O interactions make important contributions in stabilizing the TATB crystal, while other intermolecular H⋯N and H⋯C interactions, O⋯O, N⋯O, C⋯O, and C⋯N close contacts also make contributions. QTAIM analyses of the intermolecular interactions in the molecular pairs confirm the presence of these intermolecular interactions based on Hirshfeld surface analyses, indicating that these intermolecular interactions play important roles in the crystal. The reason why the TATB crystal adopts a high energy conformer in which the NO2 and NH2 groups are coplanar with the benzene ring is elaborated. The cooperativity between hydrogen bonding and π⋯π interactions in the TATB crystal is verified and illustrated. [ABSTRACT FROM AUTHOR]

Monoalkylation of aniline can be readily achieved using trichloroacetimidate as an alkylating agent and a Brønsted acid, such as (±)-camphorsulfonic acid, as a catalyst. In this study, systematic theoretical calculations were performed to understand the reaction mechanism for the monoalkylation of 2,5-dichloroaniline with trichloroacetimidate catalyzed by (±)-camphorsulfonic acid; moreover, the judgement about whether the reaction takes place via an SN1 or SN2 mechanism was elaborated. The two possible proton-transfer reaction mechanisms proposed herein based on the experimental results were investigated; moreover, another two possible reaction mechanisms involving the activation of both 2,5-dichloroaniline and trichloroacetimidate by (±)-camphorsulfonic acid via dual hydrogen-bonding activation modes were evaluated. The calculated results suggest that the reaction between 2,5-dichloroaniline and trichloroacetimidate catalyzed by (±)-camphorsulfonic acid preferentially occurs through the SN1 mechanism based on the dual hydrogen-bonding activation modes. [ABSTRACT FROM AUTHOR]

• BAATs are induced by introducing bispecific antibody and feeder cells to the traditional CIK cell culture system. • BAATs display a robust proliferation ability. • BAATs exhibit strengthened cytotoxicity at relatively low effector: target ratios. Adoptive cell therapy using ex vivo expanded lymphocytes has shown remarkable efficacy in tumor immunotherapy recently. Among various transfused immune cells, T lymphocytes are the most widely used since they are critical mediators of the immune system and have the capacity to kill tumor cells. However, there are drawbacks in the expanded T cells for transfusion including limited cytotoxicity, limited proliferation and lack of specificity. To improve the quality of these ex vivo expanded T cells, we have designed a new method to expand a group of T cells which are named bispecific antibodies activated T cells. It is the first time that such cells are induced by introducing the bispecific antibody drug (blinatumomab) and feeder cells (normal B cells and irradiated B cell originated lymphoma cells) to the traditional T cells culture system. Culture of freshly isolated human peripheral blood mononuclear cells in this newly designed cell culture system enabled these expanded T cells that (a) displayed a robust proliferation ability; (b) showed fully activated phenotype and enhanced cytokines production; (c) had a low proportion of CD4+CD25+ T regulatory cells and (d) exhibited strengthened cytotoxicity at relatively low effector: target ratios. This work further confirmed the feasibility of rapid induction and expansion of large amounts of human T cells in vitro by using bispecific antibodies and feeder cells. This strategy could also be used for other immune cells rapid expansion and help to improve the quality of these expanded immune cells for adoptive transfusion. [ABSTRACT FROM AUTHOR]

Purpose: The human peroxiredoxin-5 (hPRDX5) is a member of the family of antioxidant enzymes, which could resist immunosuppression by promoting immune organs development, lymphocyte proliferation and up-regulation of the levels of serum cytokines. However, being a recombinant protein, the hPRDX5 exhibits some problems including the high production cost and bad tissue penetration. Compared to macromolecular therapeutic agents, synthetic peptides have several advantages as drug candidates, such as lower manufacturing costs, reduced immunogenicity, and better organ or tumor penetration. The purpose of this research was to design the novel peptides come from hPRDX5 that can block the interaction of PD-1 and PD-L1.Methods: Herein in this work, we firstly confirmed the inhibitory activity of hPRDX5 on the binding of PD-L1 to PD-1 based on the previous observation, subsequently, in silico proteolysis and rational design (such as alanine scanning mutagenesis and truncation) were used to automate the design of new peptides derived from hPRDX5 with anti-tumour activity.Results: We found that the most potent peptide could block the PD-1/PD-L1 interaction effectively with an IC50 of 0.646 μM, and could restore the function of Jurkat T cells which had been suppressed by stimulated HCT116 cells. Moreover, experiments with tumor-bearing mice models showed that the peptide IMB-P6-10 could effectively inhibit tumor growth and showed extraordinary low acute toxicity in vivo.Conclusions: The peptides described in this paper may provide novel low-molecular-weight drug candidates for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Maleimide skeleton distributes widely in a great many substances, and maleimides are very useful building blocks in organic synthesis and many related disciplines, like bioconjugation. As an excellent leaving group, tosyloxy (-OTs) group are very popular in organic synthesis; however, reports on use of -OTs group on maleimide scaffold are very rare. In this study, 3-tosyloxymaleimide was prepared from l -tartaric acid and used to react with various phenols or naphthols under PTC condition to give 3-aryloxymaleimides through nucleophilic substitutions. Yields of the reaction were not high due to a competitive transesterification reaction; however, this reaction would be practical if the side-reaction could be suppressed by appropriate reaction conditions. The reaction mechanism was investigated by theoretical computation. The intermediates and transition states of the reaction, as well as the potential barrier and reaction free energy, were calculated using density functional theory (DFT), and influencing factors of the reaction were discussed. Theoretical computations showed that this nucleophilic substitution is favorable both kinetically and thermodynamically, while electron-withdrawing groups on phenols are harmful to such reactions. This study will provide new knowledge and insights on the chemical properties of maleimide and tosyloxy group, as well as the related chemical reactions. Image 1 • Nucleophilic substitutions of tosyloxy group on maleimide can occur easily. • Transesterification is a significant side-reaction when phenols are used. • This substitution reaction is favorable both kinetically and thermodynamically. • Electron-withdrawing groups on phenols are harmful to the substitution reaction. [ABSTRACT FROM AUTHOR]

Bromo- and iodo-pentafluorobenzene (C6F5X, X = Br, I) exhibit intriguing σ- and π-hole characters, which are able to accept electrons, whereas furan (C4H4O) and thiophene (C4H4S) are able to donate electrons because of their electron-rich atoms and groups (i.e., the O atom and π-ring in C4H4O and the π-ring in C4H4S). Theoretical investigations of intermolecular interactions in these systems (i.e., C4H4O and C6F5Br, C4H4S and C6F5Br, C4H4O and C6F5I, and C4H4S and C6F5I) have been carried out at the M06-2X/aug-cc-pVDZ and wB97-XD/aug-cc-pVDZ levels with and without the counterpoise method, together with single-point calculations at the CCSD(T)/aug-cc-pVDZ level. For the system of C4H4O and C6F5X (X = Br, I), five different dimers, namely, I–V and I′–V′, which are connected by σ-hole…n, σ-hole…π and π-hole…π bonds, were found. Moreover, for the system of C4H4S and C6F5Br, four different dimers, namely, VI–IX, which are connected by σ-hole…π and π-hole…π bonds, were found. However, five dimers, namely, VI′–X′, were found for the system of C4H4S and C6F5I, which are connected by σ-hole…π, π-hole…π and σ-hole…n bonds. The driving forces for the formation of these dimers were revealed by EDA analyses. NCI, QTAIM and NBO analyses were employed to prove the existence of intermolecular interactions in these dimers and to elucidate their nature. The results presented here will be insightful for the study of other intermolecular systems that involve σ- and π-holes. [ABSTRACT FROM AUTHOR]

The crystallization of 3‐chloroisonicotinic acid (3‐CINA) can lead to three crystal forms (I, II and III), but 3‐CINA in each form has different conformation. The three crystal forms have different lattice energies. The intermolecular interactions in the molecular pairs involving the conformer in each crystal were evaluated, it is found that the sum of these intermolecular interaction energies in each crystal has a linear relationship with the corresponding lattice energy. QTAIM analyses for the intermolecular interactions of molecular pairs correspond to Hirshfeld surface analyses for the crystal form, illustrating that the stability of the crystal is closely associated with the intermolecular interactions involving the conformer in the asymmetric unit of the crystal. 3‐chloroisonicotinic acid (3‐CINA) has three crystal forms (I, II and III), first principles investigation and Hirshfeld surface analysis have been employed to explore them. [ABSTRACT FROM AUTHOR]

Goat myosin light chain 6 (gMYL6) is a constituent of certain extracted immunization-induced goat anti-cancer bioactive peptides (ACBPs). However, little is known about its activity onto NK cells which are the basic cellular attackers in cancer immunotherapy for patients with malignancies. Because of the complicated extraction process and low yield of gMYL6 out of the goat ACBPs’ mixture, the Nano-flow liquid chromatography and C-terminal polycationic tag expression strategy were used to identify and enrich the peptide to investigate its bioactivity against cancers/tumors. The solubility-enhanced gMYL6 fused with a hexa-lysine tag showed a capacity of promoting the NK cells’ cytotoxicity, making it a novel promising heterogeneous peptide cytokine against cancers. [ABSTRACT FROM AUTHOR]

Bacterial resistance to most of the available antibiotics has stimulated the discovery of novel efficacious antibacterial agents. Bedaquiline is first of its type that has been specifically introduced for the management of MDR‐TB in combination with other drugs. In this study, a series of isoniazid/ethambutol/pyrazinamide/‐quinoline conjugates based on the structures of bedaquiline were designed and synthesized. Biological activity tests revealed that some of isoniazid/ethambutol/quinoline conjugates have useful antibiotic activity against MTB H37Rv (MIC: 2.0–8.0 μg/ml). Furthermore, molecular docking calculations were performed for the most potent inhibitor to show its binding interactions within the active site of the possible target protein. Overall, these compounds represent novel valuable starting point with potent antimycobacterial activity and deserve further structural modifications. [ABSTRACT FROM AUTHOR]

O2Capuramycins are antimycobacterial antibiotics that consist of a modified nucleoside named uridine-5'-carboxamide (CarU). Previous biochemical studies have revealed that CarU is derived from UMP, which is first converted to uridine-5'-aldehyde in a reaction catalyzed by the dioxygenase CapA and subsequently to 5'-Cglycyluridine (GlyU), an unusual β-hydroxy-α-amino acid, in a reaction catalyzed by the pyridoxal-5'-phosphate (PLP)-dependent transaldolase CapH. The remaining steps that are necessary to furnish CarU include decarboxylation, O atom insertion, and oxidation. We demonstrate that Cap15, which has sequence similarity to proteins annotated as bacterial, PLP-dependent L-seryl-tRNA (Sec) selenium transferases, is the sole catalyst responsible for complete conversion of GlyU to CarU. Using a complementary panel of in vitro assays, Cap15 is shown to be dependent upon substrates O2 and (5'S,6'R)-GlyU, the latter of which was unexpected given that (5'S,6'S)-GlyU is the isomeric product of the transaldolase CapH. The two products of Cap15 are identified as the carboxamide-containing CarU and CO2. While known enzymes that catalyze this type of chemistry, namely α-amino acid 2-monooxygenase, utilize flavin adenine dinucleotide as the redox cofactor, Cap15 remarkably requires only PLP. Furthermore, Cap15 does not produce hydrogen peroxide and is shown to directly incorporate a single O atom from O2 into the product CarU and thus is an authentic PLP-dependent monooxygenase. In addition to these unusual discoveries, Cap15 activity is revealed to be dependent upon the inclusion of phosphate. The biochemical characteristics along with initiatory mechanistic studies of Cap15 are reported, which has allowed us to assign Cap15 as a PLP-dependent (5'S,6'R)-GlyU: O2 monooxygenase-decarboxylase. [ABSTRACT FROM AUTHOR]

To obtain the label enzyme for enzyme-linked-immunoabsorbent-assay of two components each time in one well with conventional microplate readers, molecular engineering of Pseudomonas aeruginosa arylsulfatase (PAAS) is needed. To compare thermostability of PAAS/mutants of limited purity, effects of buffers on the half-activity time ( t ) at 37 °C were tested. At pH 7.4, PAAS showed non-exponential decreases of activity, with the apparent t of ~6.0 days in 50 mM HEPES, but ~42 days in 10 mM sodium borate with >85 % activity after 15 days; protein concentrations in both buffers decreased at slower rates after there were significant decreases of activities. Additionally, the apparent t of PAAS was ~14 days in 50 mM Tris-HCl, and ~21 days in 10 mM sodium phosphate. By sodium dodecyl-polyacrylamide gel electrophoresis, the purified PAAS gave single polypeptide; after storage for 14 days at 37 °C, there were many soluble and insoluble fragmented polypeptides in the HEPES buffer, but just one principal insoluble while negligible soluble fragmented polypeptides in the borate buffer. Of tested mutants in the neutral borate buffer, rates for activity decreases and polypeptide degradation were slower than in the HEPES buffer. Hence, dilute neutral borate buffers were favorable for examining thermostability of PAAS/mutants. [ABSTRACT FROM AUTHOR]

The high-energetic and low-sensitive explosive material of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) was theoretically investigated by first principles calculations and Hirshfeld surface analysis. The experimental and partly optimized LLM-105 crystals were compared which indicated that it is important to correct the hydrogen positions. Hirshfeld surface analyses of the experimental and partly optimized LLM-105 crystals were also compared, which showed that the intermolecular H⋯O interactions significantly contribute to the stability of the LLM-105 crystal, while the contributions of other intermolecular interactions in the experimental and partly optimized LLM-105 crystals are quite different. The geometrical and electronic structures of LLM-105 molecules in the experimental and partly optimized crystals as well as that in the gas phase were compared. QTAIM analysis was employed to illustrate the existences of intermolecular interactions in the molecular pairs taken from partly optimized LLM-105 crystal, and the types of intermolecular interactions from QTAIM analysis are in agreement with the results of Hirshfeld surface analysis. The reason why the LLM-105 molecule in the partly optimized crystal adopts a non-coplanar structure in which the NO 2 and NH 2 groups is not coplanar with the six-membered ring is elaborated. The existence of cooperativity among different intermolecular interactions were verified by analysing the trimeric complexes formed among three LLM-105 molecules in the partly optimized crystal. The non-coplanar of the NO 2 and NH 2 groups with the six-membered ring in LLM-105 molecule is favorable in forming more intermolecular interactions which cooperate and stabilize the crystal. [Display omitted] • The explosive material of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) crystal was investigated theoretically. • The single LLM-105 molecule, the dimeric and trimeric complexes were analyzed. • The non-coplanar LLM-105 molecule favors the formation of more intermolecular interactions which stabilize the crystal. • The cooperativity among the intermolecular interactions was verified. [ABSTRACT FROM AUTHOR]

Ternary NiO/Ag/RGO nanocomposites were synthesized as an electrochemical sensor for nanomolarity detection of Sunset Yellow in soft drink. [Display omitted] • Ternary NiO/Ag/RGO exhibited high electrocatalytic activity for SY oxidation. • NiO/Ag/RGO held a low LOD of 13 nM and good selectivity for SY detection. • The electrochemical sensor was successfully employed for SY detection in soft drinks. NiO nanoparticles (NPs) with small Ag NPs loading supported on reduced graphene oxide nanosheets (ternary NiO/Ag/RGO nanocomposites) were synthesized via a hydrothermal process followed by high-temperature calcination, extending the synergistic effects among noble metal, metal oxide and carbon materials. Based on ternary NiO/Ag/RGO nanocomposites, a new electrochemical sensor was fabricated for the detection of sunset yellow (SY) in soft drinks through cyclic voltammetry, Tafel plot and differential pulse voltammetry. The experimental conditions were optimized and kinetic parameters studied. Due to the synergistic effect of the ternary components, the prepared sensor exhibited superior electroanalytical performance toward SY detection, including wide linear range from 0.1 to 50 μM and from 50 to 450 μM, low detection limit of 13 nM, excellent specificity against various interfering colorants, good reproducibility and stability. Importantly, the electrochemical sensors was successfully employed for quantitative SY analysis in soft drinks with satisfactory recoveries, where the analyzed results were also in agreement with LC/MS analysis. [ABSTRACT FROM AUTHOR]

Alcohol dehydrogenase 1 identified from Artemisia annua (AaADH1) is a 40 kDa protein that predominately expressed in young leaves and buds, and catalyzes dehydrogenation of artemisinic alcohol to artemisinic aldehyde in artemisinin biosynthetic pathway. In this study, AaADH1 encoding gene was subcloned into vector pET-21a(+) and expressed in Escherichia coli. BL21(DE3), and purified by Co2+ affinity chromatography. Anion exchange chromatography was performed until the protein purity reached more than 90%. Crystallization of AaADH1 was conducted for further investigation of the molecular mechanism of catalysis, and hanging-drop vapour diffusion method was used in experiments. The results showed that the apo AaADH1 crystal diffracted to 2.95 Å resolution, and belongs to space group P1, with unit-cell parameters, a = 77.53 Å, b = 78.49 Å, c = 102.44 Å, α = 71.88°, β = 74.02°, γ = 59.97°. The crystallization condition consists of 0.1 M Bis-Tris pH 6.0, 13% (w/v) PEG 8000 and 5% (v/v) glycerol. • Alcohol dehydrogenase 1 from Artemisia annua (AaADH1) was expressed in E. coli. • Affinity chromatography and anion exchange were performed to reached over 90% purity. • Apo AaADH1 crystal diffracted to 2.95 Å resolution. • Amino acid sequence-alignment analysis of AaADH1 was conducted with depiction of protein secondary structure. [ABSTRACT FROM AUTHOR]

New drugs with novel antibacterial targets for Gram-negative bacterial pathogens are desperately needed. The protein LpxC is a vital enzyme for the biosynthesis of lipid A, an outer membrane component of Gram-negative bacterial pathogens. The ACHN-975 molecule has high enzymatic inhibitory capacity against the infectious diseases, which are caused by multidrug-resistant bacteria, but clinical research was halted because of its inflammatory response in previous studies. In this work, the structure of the recombinant UDP-3-O-(R-3-hydroxymyristol)-N-acetylglucosamine deacetylase from Aquifex aeolicus in complex with ACHN-975 was determined to a resolution at 1.21 Å. According to the solved complex structure, ACHN-975 was docked into the AaLpxC's active site, which occupied the site of AaLpxC substrate. Hydroxamate group of ACHN-975 forms five-valenced coordination with resides His74, His226, Asp230, and the long chain part of ACHN-975 containing the rigid alkynyl groups docked in further to interact with the hydrophobic area of AaLpxC. We employed isothermal titration calorimetry for the measurement of affinity between AaLpxC mutants and ACHN-975, and the results manifest the key residues (His74, Thr179, Tyr212, His226, Asp230 and His253) for interaction. The determined AaLpxC crystal structure in complex with ACHN-975 is expected to serve as a guidance and basis for the design and optimization of molecular structures of ACHN-975 analogues to develop novel drug candidates against Gram-negative bacteria. [ABSTRACT FROM AUTHOR]

Human carboxylesterase 1 (hCES1) is a major carboxylesterase in the human body and plays important roles in the metabolism of a wide variety of substances, including lipids and drugs, and therefore is attracting more and more attention from areas including lipid metabolism, pharmacokinetics, drug–drug interactions, and prodrug activation. In this work, we studied the catalytic hydrolysis mechanism of hCES1 by the quantum mechanics computation method, using cocaine as a model substrate. Our results support the four-step theory of the esterase catalytic hydrolysis mechanism, in which both the acylation stage and the deacylation stage include two transition states and a tetrahedral intermediate. The roles and cooperation of the catalytic triad, S221, H468, and E354, were also analyzed in this study. Moreover, orthoester intermediates were found in hCES1-catalyzed cocaine hydrolysis reaction, which significantly elevate the free energy barrier and slow down the reaction. Based on this finding, we propose that hCES1 substrates with β-aminocarboxylester structure might form orthoester intermediates in hCES1-catalyzed hydrolysis, and therefore prolong their in vivo half-life. Thus, this study helps to clarify the catalytic mechanism of hCES1 and elucidates important details of its catalytic process, and furthermore, provides important insights into the metabolism of hCES1 substrates and drug designing. [ABSTRACT FROM AUTHOR]

Mycobacterium tuberculosis (Mtb) has recently surpassed HIV/AIDS as the leading cause of death by a single infectious agent. The standard therapeutic regimen against tuberculosis (TB) remains a long, expensive process involving a multidrug regimen, and the prominence of multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) strains continues to impede treatment success. An underexplored class of natural products—the capuramycin-type nucleoside antibiotics—have been shown to have potent anti-TB activity by inhibiting bacterial translocase I, a ubiquitous and essential enzyme that functions in peptidoglycan biosynthesis. The present review discusses current literature concerning the biosynthesis and chemical synthesis of capuramycin and analogs, seeking to highlight the potential of the capuramycin scaffold as a favorable anti-TB therapeutic that warrants further development. [ABSTRACT FROM AUTHOR]

Human ubiquitous mitochondrial creatine kinase (uMtCK) is responsible for the regulation of cellular energy metabolism. To investigate the phosphoryl-transfer mechanism catalyzed by human uMtCK, in this work, molecular dynamic simulations of uMtCK∙ATP-Mg2+∙creatine complex and quantum mechanism calculations were performed to make clear the puzzle. The theoretical studies hereof revealed that human uMtCK utilizes a two-step dissociative mechanism, in which the E227 residue of uMtCK acts as the catalytic base to accept the creatine guanidinium proton. This catalytic role of E227 was further confirmed by our assay on the phosphatase activity. Moreover, the roles of active site residues in phosphoryl transfer reaction were also identified by site directed mutagenesis. This study reveals the structural basis of biochemical activity of uMtCK and gets insights into its phosphoryl transfer mechanism. [ABSTRACT FROM AUTHOR]