Enzyme Cavity Research Articles

Microbial Enzymes for the Biodegradation of Polylactic Acid (PLA): Molecular Docking Simulation and Biodegradation Pathway Proposal

Polylactic acid (PLA), as a biodegradable polymer, finds widespread utility across diverse sectors, encompassing transportation, agriculture, biomedicine, textiles, electronics, and food packaging. Nonetheless, its degradation kinetics exhibit significant environmental sensitivity, necessitating the development of novel biotechnological methodologies to investigate the microbial and enzymatic constituents implicated in PLA biodegradation. In this review, molecular docking simulations are discussed to analyze the enzymatic degradation of PLA using specific enzymes: proteinase K, PLA depolymerase, and lipase. The binding energy, binding affinity, and dimensions of PLA-binding sites within the enzyme cavities have been examined for each enzyme. The binding amino acid residues mainly include serine, histidine, and aspartate for all plastics, while the interactions involve Van der Waals forces, conventional hydrogen bonding, carbon-hydrogen bonding, and Pi-interactions. Based on our synthesis of the literature, a theoretical PLA biodegradation pathway that illustrates the interaction pattern between PLA and the enzymes, as well as the degradation mechanism is proposed. Our review indicates that in natural environments, enzymes work synergistically, utilizing their unique properties to facilitate an efficient sequential catalytic process for PLA degradation. This integrative approach elucidates the mechanistic underpinnings and metabolic cascades governing PLA degradation, enriching insights into enzymatic catalysis and microbial enzyme-mediated plastic biotransformation. Consequently, a comprehensive understanding of these processes is paramount in optimizing biodegradation kinetics and enhancing the environmental performance of biodegradable polymers. This review provides a detailed framework for refining PLA management strategies and advancing sustainable polymer utilization.

Chalcone Derivatives as Antibacterial Agents: An Updated Overview.

The indiscriminate use of antibiotics brings an alarming reality: in 2050, bacterial resistance could be the main cause of death in the world, resulting in the death of 10 million people, according to the World Health Organization (WHO). In this sense, to combat bacterial resistance, several natural substances, including chalcones, have been described in relation to antibacterial, representing a potential tool for the discovery of new antibacterial drugs. The objective of this study is to perform a bibliographic survey and discuss the main contributions in the literature about the antibacterial potential of chalcones in the last 5 years. A search was carried out in the main repositories, for which the publications of the last 5 years were investigated and discussed. Unprecedented in this review, in addition to the bibliographic survey, molecular docking studies were carried out to exemplify the applicability of using one of the molecular targets for the design of new entities with antibacterial activity. In the last 5 years, antibacterial activities were reported for several types of chalcones, for which activities were observed for both gram-positive and gram-negative bacteria with high potency, including MIC values in the nanomolar range. Molecular docking simulations demonstrated important intermolecular interactions between chalcones and residues from the enzymatic cavity of the enzyme DNA gyrase, one of the validated molecular targets in the development of new antibacterial agents. The data presented demonstrate the potential of using chalcones in drug development programs with antibacterial properties, which may be useful to combat resistance, a worldwide public health problem.

Catalytic specificity and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa

The escalating drug resistance among microorganisms underscores the urgent need for innovative therapeutic strategies and a comprehensive understanding of bacteria's defense mechanisms against oxidative stress and antibiotics. Among the recently discovered barriers, the endogenous production of hydrogen sulfide (H2S) via the reverse transsulfuration pathway, emerges as a noteworthy factor. In this study, we have explored the catalytic capabilities and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa (PaCGL), a multidrug-opportunistic pathogen chiefly responsible for nosocomial infections. In addition to a canonical l-cystathionine hydrolysis, PaCGL efficiently catalyzes the production of H2S using l-cysteine and/or l-homocysteine as alternative substrates. Comparative analysis with the human enzyme and counterparts from other pathogens revealed distinct structural features within the primary enzyme cavities. Specifically, a distinctly folded entrance loop could potentially modulate the access of substrates and/or inhibitors to the catalytic site. Our findings offer significant insights into the structural evolution of CGL enzymes across different pathogens and provide novel opportunities for developing specific inhibitors targeting PaCGL.

Elucidation of factors shaping reactivity of 5'-deoxyadenosyl - a prominent organic radical in biology.

This study investigates the factors modulating the reactivity of 5'-deoxyadenosyl (5'dAdo˙) radical, a potent hydrogen atom abstractor that forms in the active sites of radical SAM enzymes and that otherwise undergoes a rapid self-decay in aqueous solution. Here, we compare hydrogen atom abstraction (HAA) reactions between native substrates of radical SAM enzymes and 5'dAdo˙ in aqueous solution and in two enzymatic microenvironments. With that we reveal that HAA efficiency of 5'dAdo˙ is due to (i) the in situ formation of 5'dAdo˙ in a pre-ordered complex with a substrate, which attenuates the unfavorable effect of substrate:5'dAdo˙ complex formation, and (ii) the prevention of the conformational changes associated with self-decay by a tight active-site cavity. The enzymatic cavity, however, does not have a strong effect on the HAA activity of 5'dAdo˙. Thus, we performed an analysis of in-water HAA performed by 5'dAdo˙ based on a three-component thermodynamic model incorporating the diagonal effect of the free energy of reaction, and the off-diagonal effect of asynchronicity and frustration. To this aim, we took advantage of the straightforward relationship between the off-diagonal thermodynamic effects and the electronic-structure descriptor - the redistribution of charge between the reactants during the reaction. It allows to access HAA-competent redox and acidobasic properties of 5'dAdo˙ that are otherwise unavailable due to its instability upon one-electron reduction and protonation. The results show that all reactions feature a favourable thermodynamic driving force and tunneling, the latter of which lowers systematically barriers by ∼2 kcal mol-1. In addition, most of the reactions experience a favourable off-diagonal thermodynamic contribution. In HAA reactions, 5'dAdo˙ acts as a weak oxidant as well as a base, also 5'dAdo˙-promoted HAA reactions proceed with a quite low degree of asynchronicity of proton and electron transfer. Finally, the study elucidates the crucial and dual role of asynchronicity. It directly lowers the barrier as a part of the off-diagonal thermodynamic contribution, but also indirectly increases the non-thermodynamic part of the barrier by presumably controlling the adiabatic coupling between proton and electron transfer. The latter signals that the reaction proceeds as a hydrogen atom transfer rather than a proton-coupled electron transfer.

Antimicrobial activity of novel substituted 1,2,4-triazole and 1,3-thiazole derivatives

In this work, thirteen new compounds have been synthesized, characterized and evaluated for their antifungal and antimicrobial activities. Seven of them which contain the thiazole ring were obtained by reacting 2-(2-(2-methoxyphenoxy)propanoyl)-N-phenylhydrazine-1-carbothioamide (3) with phenylacyl bromide derivatives, while the other six compounds that have the 1,2,4-triazole ring (6a-6f) were prepared through couple of steps starting from the same intermediate 2-(2-(2-methoxyphenoxy)acetyl)-N-phenylhydrazine-1-carbothioamide (3). All final compounds were characterized using LC-MS, 1HNMR and 13CNMR spectroscopic techniques. All compounds were tested against twelve bacterial strains and ten fungus species. Derivative (5a) that is N'-(3,4-diphenylthiazol-2(3H)-ylidene)-2(methoxyphenoxy)propanehydrazide had shown the best activity and selectivity toward Yersinia enterocolitica bacterial type. All compounds demonstrated good activity against filamentous fungi species compared to yeast species. Molecular docking studies also showed that derivatives 2-(2-Methoxyphenoxy)-N'-(4-(4-methoxyphenyl)-3-phenylthiazol-2(3H)-ylidene)propanehydrazide (5c), N'-(4-(4-chlorophenyl)-3-phenylthiazol-2(3H)-ylidene)-2-(2-methoxyphenoxy)propanehydrazide (5d) and N-(4-(4-fluorophenyl)-3-phenylthiazol-2(3H)-ylidene)-2-(2-methoxyphenoxy)propanehydrazide (5e) interacted with the active cavity of lanosterol 14α-demethylase enzyme.

Imidazopyridine-Based Thiazole Derivatives as Potential Antidiabetic Agents: Synthesis, In Vitro Bioactivity, and In Silico Molecular Modeling Approach.

A new series of thiazole derivatives (4a-p) incorporating imidazopyridine moiety was synthesized and assessed for their in vitro potential α-glucosidase potency using acarbose as a reference drug. The obtained results suggested that compounds 4a (docking score = -13.45), 4g (docking score = -12.87), 4o (docking score = -12.15), and 4p (docking score = -11.25) remarkably showed superior activity against the targeted α-glucosidase enzyme, with IC50 values of 5.57 ± 3.45, 8.85 ± 2.18, 7.16 ± 1.40, and 10.48 ± 2.20, respectively. Upon further investigation of the binding mode of the interactions by the most active scaffolds with the α-glucosidase active sites, the docking analysis was accomplished in order to explore the active cavity of the α-glucosidase enzyme. The interpretation of the results showed clearly that scaffolds 4a and 4o emerged as the most potent α-glucosidase inhibitors, with promising excellent binding interactions with the active site of the α-glucosidase enzyme. Furthermore, utilizing a variety of spectroscopic methods, such as 1H-NMR, 13C-NMR, and HREI-MS, the precise structures of the synthesized scaffolds were determined.

Synthesis, biological evaluation and molecular modeling studies of modulated benzyloxychalcones as potential acetylcholinesterase inhibitors

Acetylcholinesterase inhibitors (AChEIs) have become a significant target in the search for an efficient treatment of Alzheimer’s disease. Chalcone-based compounds display a strong potency to hinder AChE. So, this study focused on the synthesis of a series of new chalcone derivatives with anti-cholinesterase potential and their structures were characterized based on spectroscopic methods including IR, 1H NMR, 13C NMR and HRMS. Chalcone derivatives were screened against AChE. Most of them exhibited potent inhibitory activity against AChE. Compound 11i showed the most potent activity toward acetylcholinesterase compared to the positive compound, Galantamine. Docking studies into the active site of the acetylcholinesterase enzyme ravealed the significant docking score of the synthesized compounds with docking score of −7.959 to −9.277 kcal/mol when compared to the co-crystallized ligand, Donepezil (−10.567 kcal/mol). The interaction’s stability was further assessed using a conventional atomistic 100 ns dynamics simulation study, which revealed the conformational stability of representative compound 11i in the cavity of the acetylcholinesterase enzyme. Communicated by Ramaswamy H. Sarma

Novel Reversible Inhibitors of Xanthine Oxidase Targeting the Active Site of the Enzyme.

Xanthine oxidase (XO) is a flavoprotein catalysing the oxidation of hypoxanthine to xanthine and then to uric acid, while simultaneously producing reactive oxygen species. Altered functions of XO may lead to severe pathological diseases, including gout-causing hyperuricemia and oxidative damage of tissues. These findings prompted research studies aimed at targeting the activity of this crucial enzyme. During the course of a virtual screening study aimed at the discovery of novel inhibitors targeting another oxidoreductase, superoxide dismutase, we identified four compounds with non-purine-like structures, namely ALS-1, -8, -15 and -28, that were capable of causing direct inhibition of XO. The kinetic studies of their inhibition mechanism allowed a definition of these compounds as competitive inhibitors of XO. The most potent molecule was ALS-28 (Ki 2.7 ± 1.5 µM), followed by ALS-8 (Ki 4.5 ± 1.5 µM) and by the less potent ALS-15 (Ki 23 ± 9 µM) and ALS-1 (Ki 41 ± 14 µM). Docking studies shed light on the molecular basis of the inhibitory activity of ALS-28, which hinders the enzyme cavity channel for substrate entry consistently with the competitive mechanism observed in kinetic studies. Moreover, the structural features emerging from the docked poses of ALS-8, -15 and -1 may explain the lower inhibition power with respect to ALS-28. All these structurally unrelated compounds represent valuable candidates for further elaboration into promising lead compounds.

Enzymatic reversion of Pt(II) nucleophilicity through charge dumping: the case of Pt(CN)42.

Combining computations and X-ray structure analysis we have demonstrated that [Pt(CN4)]2- can behave as a Lewis acid inside an enzyme's cavity. The nature of a counterintuitive contact found between a catalytically active GLN residue belonging to a mitochondrial synthase and the Pt(II) center was investigated by combining molecular dynamics and quantum mechanics calculations. Results confirm the electron acceptor role of [Pt(CN4)]2-, serving as an inspiration for the design of biomolecular cages able to tweak the nucleophilic/electrophilic character of an organometallic compound.

Control of reactivity and selectivity in isomerization and rearrangement reactions inside confined spaces.

In the confined space of supramolecular systems, the substrate can be forced into a reactive conformation and labile intermediates may be stabilized while isolated from the bulk solution. In this highlight, unusual processes mediated by supramolecular hosts are described. These include unfavourable conformational equilibria, unusual product selectivities in bond and ring-chain isomerizations, accelerated rearrangement reactions through labile intermediates, and encapsulated oxidations. In the host, controlled or altered isomerization of the guests can occur via hydrophobic, photochemical and thermal interventions. The inner spaces of the hosts resemble enzyme cavities that stabilize labile intermediates not accessible in the bulk solvent. The effects of confinement and the binding forces involved are discussed and further applications are suggested.

Inhibition mechanisms of wounded okra on the α-glucosidase/α-amylase

Okra has attracted increasing interests to be used as functional food ingredients due to various human health benefits such as the inhibition of α-glucosidase and α-amylase in this paper. Results showed that the α-glucosidase (and α-amylase) inhibition capacity of polyphenols in wounded okra significantly increased by 31.6% (and 28.6%) when the wounding intensity was 1.87 cm2/g. The UPLC-MS analysis indicated that quercetin and catechin derivatives were the major polyphenols in wounded okra, of which quercetin 3-O-gentiobioside and epigallocatechin dimer were the most abundant compounds. Fluorescence quenching confirmed that wound and healing process promoted the affinity between α-glucosidase (and α-amylase) and polyphenols, which interacted with enzymes in a mixed type manner. Molecular docking suggested that quercetin-3-O-gentiobioside, quercetin-3-O-glucosyl-xyloside, isoquercitrin, querce-tin-3-O-(malonyl)-glucoside, epigallocatechin, and epigallocatechin dimer can interact with the activity cavities of enzymes by amino acids residues (Arg195, Leu162, and His305). The results of this study support the potentials of wounded okra to inhibit α-glucosidase and α-amylase in the food industries, without associated risks to consumers.

Design and Evaluation of Novel HIV-1 Protease Inhibitors Containing Phenols or Polyphenols as P2 Ligands with High Activity against DRV-Resistant HIV-1 Variants.

With the increasing prevalence of drug-resistant variants, novel potent HIV-1 protease inhibitors with broad-spectrum antiviral activity against multidrug-resistant causative viruses are urgently needed. Herein, we designed and synthesized a new series of HIV-1 protease inhibitors with phenols or polyphenols as the P2 ligands and a variety of sulfonamide analogs as the P2' ligands. A number of these new inhibitors showed superb enzymatic inhibitory activity and antiviral activity. In particular, inhibitors 15d and 15f exhibited potent enzymatic inhibitory activity in the low picomolar range, and the latter showed excellent activity against the Darunavir-resistant HIV-1 variant. Furthermore, the molecular modeling studies provided insight into the ligand-binding site interactions between inhibitors and the enzyme cavity, and they sparked inspiration for the further optimization of potent inhibitors.

Protection against Oxidative Stress and Metabolic Alterations by Synthetic Peptides Derived from Erythrina edulis Seed Protein.

The ability of multifunctional food-derived peptides to act on different body targets make them promising alternatives in the prevention/management of chronic disorders. The potential of Erythrina edulis (pajuro) protein as a source of multifunctional peptides was proven. Fourteen selected synthetic peptides identified in an alcalase hydrolyzate from pajuro protein showed in vitro antioxidant, anti-hypertensive, anti-diabetic, and/or anti-obesity effects. The radical scavenging properties of the peptides could be responsible for the potent protective effects observed against the oxidative damage caused by FeSO4 in neuroblastoma cells. Moreover, their affinity towards the binding cavity of angiotensin-converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) were predicted by molecular modeling. The results demonstrated that some peptides such as YPSY exhibited promising binding at both enzymes, supporting the role of pajuro protein as a novel ingredient of functional foods or nutraceuticals for prevention/management of oxidative stress, hypertension, and metabolic-alteration-associated chronic diseases.

Experimental and Computational Analysis of Newly Synthesized Benzotriazinone Sulfonamides as Alpha-Glucosidase Inhibitors.

Diabetes mellitus is a chronic metabolic disorder in which the pancreas secretes insulin but the body cells do not recognize it. As a result, carbohydrate metabolism causes hyperglycemia, which may be fatal for various organs. This disease is increasing day by day and it is prevalent among people of all ages, including young adults and children. Acarbose and miglitol are famous alpha-glucosidase inhibitors but they complicate patients with the problems of flatulence, pain, bloating, diarrhea, and loss of appetite. To overcome these challenges, it is crucial to discover new anti-diabetic drugs with minimal side effects. For this purpose, benzotriazinone sulfonamides were synthesized and their structures were characterized by FT-IR, 1H-NMR and 13C-NMR spectroscopy. In vitro alpha-glucosidase inhibition studies of all synthesized hybrids were conducted using the spectrophotometric method. The synthesized compounds revealed moderate-to-good inhibition activity; in particular, nitro derivatives 12e and 12f were found to be the most effective inhibitors against this enzyme, with IC50 values of 32.37 ± 0.15 µM and 37.75 ± 0.11 µM. In silico studies, including molecular docking as well as DFT analysis, also strengthened the experimental findings. Both leading compounds 12e and 12f showed strong hydrogen bonding interactions within the enzyme cavity. DFT studies also reinforced the strong binding interactions of these derivatives with biological molecules due to their lowest chemical hardness values and lowest orbital energy gap values.

Repositioning of tubocurarine as analgesic and anti-inflammatory agent: Exploring beyond myorelaxant activity

Background and purposeTubocurarine (d-TC), a non-depolarizing competitive blocker of nicotinic acetylcholine receptors is extensively utilized for the relaxation of skeletal muscles. Drug repositioning is a forthright approach to reduce the cost and speed up drug development process. Herein, we have attempted to evaluate the analgesic and anti-inflammatory activity of d-TC for its possible repurposing in pain and inflammation-related issues.Experimental approach.We examined the soluble epoxide hydrolase inhibitory (sEHI) activity of d-TC employing in silico high throughput screening protocols, in vitro cell-free sEH inhibitory assay, and in in vivo rodent models for its repositioning in pain and inflammation-related disorders.Key results.In molecular docking study, d-TC displayed impressive hydrogen bonding interactions within the cavity of sEH enzyme with good docking score. d-TC also exhibited notable sEH inhibitory activity (IC50 3.72 nm) at the in vitro assay. Oral absorption capability of d-TC (0.1 and 0.2 mg/mL) was determined using an in vitro everted intestinal sac model employing rat ileum tissue that revealed significant oral absorption of d-TC. Besides, in vivo studies revealed that oral administration of d-TC (0.1 and 0.2 mg/kg) in rodents significantly attenuated hyperalgesia (cold plate test, tail immersion test and formalin test) and inflammation (estimation of rectal temperature, acetic acid induced pleurisy test and cotton pellet-induced granuloma test) induced in robust preclinical models.Conclusion and implicationsThese findings are novel and warrant immediate efforts to reposition d-TC as a new therapeutic candidate in the management of hyperalgesia, inflammation, and associated conditions.

Thiosemicarbazide-Substituted Coumarins as Selective Inhibitors of the Tumor Associated Human Carbonic Anhydrases IX and XII.

A novel series of thiosemicarbazide-substituted coumarins was synthesized and the inhibitory effects against four physiologically relevant carbonic anhydrase isoforms I, II, IX and XII showed selective activities on the tumor-associated IX and XII isozymes. Molecular modeling studies on selected compounds 14a and 22a were performed. The binding modes of such compounds were determined assuming their enzymatically active structures (i.e., cinnamic acid) in the thermodynamically favored, and not previously explored, E geometry. Molecular modelling suggests multiple interactions within the enzymatic cavity and may explain the high potency and selectivity reported for the hCAs IX and XII.

Coordination Chemistry of Nucleotides and Antivirally Active Acyclic Nucleoside Phosphonates, including Mechanistic Considerations.

Considering that practically all reactions that involve nucleotides also involve metal ions, it is evident that the coordination chemistry of nucleotides and their derivatives is an essential corner stone of biological inorganic chemistry. Nucleotides are either directly or indirectly involved in all processes occurring in Nature. It is therefore no surprise that the constituents of nucleotides have been chemically altered—that is, at the nucleobase residue, the sugar moiety, and also at the phosphate group, often with the aim of discovering medically useful compounds. Among such derivatives are acyclic nucleoside phosphonates (ANPs), where the sugar moiety has been replaced by an aliphatic chain (often also containing an ether oxygen atom) and the phosphate group has been replaced by a phosphonate carrying a carbon–phosphorus bond to make the compounds less hydrolysis-sensitive. Several of these ANPs show antiviral activity, and some of them are nowadays used as drugs. The antiviral activity results from the incorporation of the ANPs into the growing nucleic acid chain—i.e., polymerases accept the ANPs as substrates, leading to chain termination because of the missing 3′-hydroxyl group. We have tried in this review to describe the coordination chemistry (mainly) of the adenine nucleotides AMP and ATP and whenever possible to compare it with that of the dianion of 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA2− = adenine(N9)-CH2-CH2-O-CH2-) [or its diphosphate (PMEApp4−)] as a representative of the ANPs. Why is PMEApp4− a better substrate for polymerases than ATP4−? There are three reasons: (i) PMEA2− with its anti-like conformation (like AMP2−) fits well into the active site of the enzyme. (ii) The phosphonate group has an enhanced metal ion affinity because of its increased basicity. (iii) The ether oxygen forms a 5-membered chelate with the neighboring phosphonate and favors thus coordination at the Pα group. Research on ANPs containing a purine residue revealed that the kind and position of the substituent at C2 or C6 has a significant influence on the biological activity. For example, the shift of the (C6)NH2 group in PMEA to the C2 position leads to 9-[2-(phosphonomethoxy)ethyl]-2-aminopurine (PME2AP), an isomer with only a moderate antiviral activity. Removal of (C6)NH2 favors N7 coordination, e.g., of Cu2+, whereas the ether O atom binding of Cu2+ in PMEA facilitates N3 coordination via adjacent 5- and 7-membered chelates, giving rise to a Cu(PMEA)cl/O/N3 isomer. If the metal ions (M2+) are M(α,β)-M(γ)-coordinated at a triphosphate chain, transphosphorylation occurs (kinases, etc.), whereas metal ion binding in a M(α)-M(β,γ)-type fashion is relevant for polymerases. It may be noted that with diphosphorylated PMEA, (PMEApp4−), the M(α)-M(β,γ) binding is favored because of the formation of the 5-membered chelate involving the ether O atom (see above). The self-association tendency of purines leads to the formation of dimeric [M2(ATP)]2(OH)− stacks, which occur in low concentration and where one half of the molecule undergoes the dephosphorylation reaction and the other half stabilizes the structure—i.e., acts as the “enzyme” by bridging the two ATPs. In accord herewith, one may enhance the reaction rate by adding AMP2− to the [Cu2(ATP)]2(OH)− solution, as this leads to the formation of mixed stacked Cu3(ATP)(AMP)(OH)− species, in which AMP2− takes over the structuring role, while the other “half” of the molecule undergoes dephosphorylation. It may be added that Cu3(ATP)(PMEA) or better Cu3(ATP)(PMEA)(OH)− is even a more reactive species than Cu3(ATP)(AMP)(OH)−. – The matrix-assisted self-association and its significance for cell organelles with high ATP concentrations is summarized and discussed, as is, e.g., the effect of tryptophanate (Trp−), which leads to the formation of intramolecular stacks in M(ATP)(Trp)3− complexes (formation degree about 75%). Furthermore, it is well-known that in the active-site cavities of enzymes the dielectric constant, compared with bulk water, is reduced; therefore, we have summarized and discussed the effect of a change in solvent polarity on the stability and structure of binary and ternary complexes: Opposite effects on charged O sites and neutral N sites are observed, and this leads to interesting insights.

Characterization of a Recombinant Laccase B from Trametes hirsuta MX2 and Its Application for Decolorization of Dyes.

Trametes hirsuta is able to secrete laccase isoenzymes including constitutive and inducible forms, and has potential application for bioremediation of environmental pollutants. Here, an inducible group B laccase from T. hirsuta MX2 was heterologously expressed in Pichia pastoris, and its yield reached 2.59 U/mL after 5 days of methanol inducing culture. The optimal pH and temperature of recombinant laccase (rLac1) to 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) were 2.5 and 60 °C, respectively. Metal ions showed different effect on rLac1 which Mg2+, Cu2+, and K+ increased enzyme activity as their concentration increased, whereas Zn2+, Na+, and Fe2+ inhibited enzyme activity as their concentration increased. rLac1 showed good tolerance to organic solvents, and more than 42% of its initial activity remained in 10% organic solvents. Additionally, rLac1 exhibited a more efficient decolorization ability for remazol brilliant blue R (RBBR) than for acid red 1 (AR1), crystal violet (CV), and neutral red (NR). Molecular docking results showed RBBR has a stronger binding affinity with laccase than other dyes by interacting with substrate binding cavity of enzyme. The results indicated rLac1 may be a potential candidate for dye removal from textile wastewater.

A Cysteine Variant at an Allosteric Site Alters MIF Dynamics and Biological Function in Homo- and Heterotrimeric Assemblies.

Macrophage migration inhibitory factor (MIF) is an inflammatory protein with various non-overlapping functions. It is not only conserved in mammals, but it is found in parasites, fish, and plants. Human MIF is a homotrimer with an enzymatic cavity between two subunits with Pro1 as a catalytic base, activates the receptors CD74, CXCR2, and CXCR4, has functional interactions in the cytosol, and is reported to be a nuclease. There is a solvent channel down its 3-fold axis with a recently identified gating residue as an allosteric site important for regulating, to different extents, the enzymatic activity and CD74 binding and signaling. In this study we explore the consequence of converting the allosteric residue Tyr99 to cysteine (Y99C) and characterize its crystallographic structure, NMR dynamics, stability, CD74 function, and enzymatic activity. In addition to the homotrimeric variant, we develop strategies for expressing and purifying a heterotrimeric variant consisting of mixed wild type and Y99C for characterization of the allosteric site to provide more insight.

Substantiating the mechanism of Boswellic acids through molecular docking study

Inflammation is the first response shown by the immune system in defense to any attack by bacteria or viruses. Inflammation is responsible for contributing to half of the world’s global burden of disease. It is mainly characterized by pain (dolor), heat (calor), swelling (tumor), and redness (rubor). The inflammatory cascades are the sole reasons for many musculoskeletal disorders. These musculoskeletal disorders are prevalent throughout the world, with a ubiquitous impact leading to long-term pain and disability. They significantly affect the psychosocial status of people who have them. Boswellic acids (BA), a natural mixture isolated from oleo gum resin of Boswellia serrata comprised of four major pentacyclic triterpene acids: Beta-BA, 3-acteyl beta BA, 11-keto-beta-BA, and 3-acetyl-11-keto-beta-BA, isolated from the oleo gum resin of B. serrata is reported to be effective as anti-inflammatory, immunomodulatory, anti-tumor, anti-asthmatic and in chronic colitis. Its anti-inflammatory activity has been attributed to the inhibition of 5-lipoxygenase in a selective, enzyme-linked non-redox, and non-competitive manner. The anti-asthmatic reports on BA revealed that leukotriene and elastase enzyme inhibition might be responsible for this effect. Although BA acts through several mechanisms for its biological activities, the inhibition of leukotrienes is the primary and the most scientifically proved mechanism. This work substantiates the effect of B. serrata BAs through molecular docking study into the cavity of 5-LOX enzyme.