Showing papers on "Non-competitive inhibition published in 2016"
TL;DR: Combined kinetics and fluorescence quenching studies can be applied to characterise the interactions between polyphenols in young apples and α-amylase, revealing that YAP and tannic acid were competitive inhibitors of PPA, whereas chlorogenic acid and caffeic Acid were mixed inhibitors, exhibiting both competitive and uncompetitive characteristics.
131 citations
TL;DR: In this paper, the inhibitory properties of three tea extracts and individual phenolic compounds against porcine pancreatic α-amylase (PPA) were studied by measuring their half inhibitory (IC50) concentrations through Dixon, Cornish-Bowden, and Lineweaver-Burk plots.
97 citations
TL;DR: In this paper, the authors investigated the inhibitory properties of five dietary flavonoids (pinobanksin, galangin, pinocembrin, 7-O-β- d -glucopyranoside and glabranin).
62 citations
TL;DR: DCF as well as E2G can be used as sensitive probes for in vitro OATP1B1 inhibition assays, which will help mitigate the risk of false-negative DDI predictions potentially caused by substrate-dependent Ki variations.
Abstract: Organic anion transporting polypeptide (OATP) 1B1 plays an important role in the hepatic uptake of various drugs. Because OATP1B1 is a site of drug-drug interactions (DDIs), evaluating the inhibitory potential of drug candidates on OATP1B1 is required during drug development. For establishing a highly sensitive, high-throughput fluorescence-based OATP1B1 inhibition assay system, the present study focused on fluorescein (FL) and its derivatives and evaluated their uptake via OATP1B1 as well as OATP1B3 and OATP2B1 using the transporter-expressing human embryonic kidney 293 cells. We identified 2',7'-dichlorofluorescein (DCF), 4',5'-dibromofluorescein (DBF), and Oregon green (OG) as good OATP1B1 substrates with Km values of 5.29, 4.16, and 54.1 μM and Vmax values of 87.9, 48.1, and 187 pmol/min/mg protein, respectively. In addition to FL, fluo-3, and 8-fluorescein-cAMP, OG, and DBF were identified as OATP1B3 substrates. FL, OG, DCF, and DBF were identified as OATP2B1 substrates. Among the FL derivatives, DCF displayed the highest OATP1B1-mediated uptake. The Ki values of 14 compounds on OATP1B1 determined with DCF as a probe exhibited good agreement with those obtained using [(3)H]estradiol-17β-glucuronide (E2G) as a substrate, whereas [(3)H]estrone-3-sulfate and [(3)H]sulfobromophthalein yielded higher Ki values for all inhibitors than DCF. Mutually competitive inhibition observed between DCF and E2G suggested that they share the same binding site on OATP1B1. Therefore, DCF as well as E2G can be used as sensitive probes for in vitro OATP1B1 inhibition assays, which will help mitigate the risk of false-negative DDI predictions potentially caused by substrate-dependent Ki variations.
43 citations
TL;DR: Results indicated that the leaves of Smilax china L. may contain compounds with anti-diabetic activity and molecular docking study for the competitive inhibitors (6, 11, and 12) radically corroborates the binding affinities and inhibition of PTP1B enzymes.
40 citations
TL;DR: A novel series of N-arylbenzo[d]oxazol-2-amines (4a-4m) were synthesized and evaluated for their α-glucosidase inhibitory activity and it was found that compound 4g having 4-phenoxy substitution at the phenyl ring was found to be the most active inhibitor of α- glucosdase.
37 citations
TL;DR: Plumbagin presented non-time-dependent inhibition of CYP activities in both human and rat liver and the relatively low Ki values of plumbagin in humans would have a high potential to cause the toxicity and drug interactions involving CYP enzymes.
Abstract: Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone), a natural naphthoquinone compound isolated from roots of Plumbago zeylanica L., has drawn a lot of attention for its plenty of pharmacological properties including antidiabetes and anti-cancer. The aim of this study was to investigate the effects of plumbagin on CYP1A2, CYP2B1/6, CYP2C9/11, CYP2D1/6, CYP2E1 and CYP3A2/4 activities in human and rat liver and evaluate the potential herb-drug interactions using the cocktail approach. All CYP substrates and their metabolites were analyzed using high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS). Plumbagin presented non-time-dependent inhibition of CYP activities in both human and rat liver. In humans, plumbagin was not only a mixed inhibitor of CYP2B6, CYP2C9, CYP2D6, CYP2E1 and CYP3A4, but also a non-competitive inhibitor of CYP1A2, with Ki values no more than 2.16 μM. In rats, the mixed inhibition of CYP1A2 and CYP2D1, and competitive inhibition for CYP2B1, CYP2C11 and CYP2E1 with Ki values less than 9.93 μM were observed. In general, the relatively low Ki values of plumbagin in humans would have a high potential to cause the toxicity and drug interactions involving CYP enzymes.
36 citations
TL;DR: The structure of the urease-sulfite complex, determined at 1.65Å resolution, shows the inhibitor bound to the dinuclear Ni(II) center of Urease in a tridentate mode involving bonds between the two Ni( II) ions in the active site and all three oxygen atoms of the inhibitor, supporting the observed competitive inhibition kinetics.
35 citations
TL;DR: Using this principle, sensors for toxic substances, like mercury, cadmium, cyanide, and azide, were designed using urease and catalase‐powered pumps, respectively, with limits of detection well below the concentrations permitted by the Environmental Protection Agency.
Abstract: Rapid, easy-to-use, and portable devices that can provide a read-out without the need for expensive equipment represent the future of sensing technology, with applications in areas like environmental, food, chemical, and biological safety. Enzymes immobilized on a surface function as micropumps in the presence of species (e.g., substrate, cofactor, or biomarker) that trigger the enzymatic reaction. The flow speed in these devices increases with increasing reaction rate. This allows the detection of substances that inhibit the enzymatic reaction. Using this principle, sensors for toxic substances, like mercury, cadmium, cyanide, and azide, were designed using urease and catalase-powered pumps, respectively, with limits of detection well below the concentrations permitted by the Environmental Protection Agency. The study was also extended to other inhibitors for these enzymes. The sensing range of fluid flow-based inhibitor assays depends on the type of inhibition, the enzyme concentration on the sensing platform, and, for competitive inhibition, the concentration of substrate used.
35 citations
TL;DR: Overall, sulfated coumarins represent first-in-class, sub-maximal inhibitors of thrombin and establish the concept of allosteric partial inhibition of soluble, monomeric proteins, which may lead to a new class of anticoagulants that are completely devoid of bleeding.
Abstract: Allosteric partial inhibition of soluble, monomeric proteases can offer major regulatory advantages, but remains a concept on paper to date; although it has been routinely documented for receptors and oligomeric proteins. Thrombin, a key protease of the coagulation cascade, displays significant conformational plasticity, which presents an attractive opportunity to discover small molecule probes that induce sub-maximal allosteric inhibition. We synthesized a focused library of some 36 sulfated coumarins to discover two agents that display sub-maximal efficacy (~50%), high potency ( 150-fold). Michaelis-Menten, competitive inhibition, and site-directed mutagenesis studies identified exosite 2 as the site of binding for the most potent sulfated coumarin. Stern-Volmer quenching of active site-labeled fluorophore suggested that the allosteric regulators induce intermediate structural changes in the active site as compared to those that display ~80-100% efficacy. Antithrombin inactivation of thrombin was impaired in the presence of the sulfated coumarins suggesting that allosteric partial inhibition arises from catalytic dysfunction of the active site. Overall, sulfated coumarins represent first-in-class, sub-maximal inhibitors of thrombin. The probes establish the concept of allosteric partial inhibition of soluble, monomeric proteins. This concept may lead to a new class of anticoagulants that are completely devoid of bleeding.
32 citations
TL;DR: Loganin, morroniside, and 7-O-galloyl-d-sedoheptulose together can act as a triple inhibitor of AChE, butyrylcholinesterase, and BACE1, providing a preventive and therapeutic strategy for Alzheimer’s disease treatment.
Abstract: We evaluated the major active components isolated from Corni Fructus: loganin, morroniside, and 7-O-galloyl-d-sedoheptulose as inhibitors of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) for use in Alzheimer’s disease treatment. These compounds exhibited predominant cholinesterase (ChEs) inhibitory effects with IC50 values of 0.33, 3.95, and 10.50 ± 1.16 µM, respectively, for AChE, and 33.02, 37.78, and 87.94 ± 4.66 µM, respectively, for BChE. Kinetics studies revealed that loganin and 7-O-galloyl-d-sedoheptulose inhibited AChE with characteristics typical of mixed inhibitors, while morroniside was found to be a noncompetitive inhibitor against AChE and also exerted mixed BChE inhibitory activities. For BACE1, loganin showed noncompetitive type inhibitory effects, while morroniside and 7-O-galloyl-d-sedoheptulose were found to be mixed inhibitors. Furthermore, these compounds exhibited dose-dependent inhibitory activity with ONOO−-mediated protein tyrosine nitration. Molecular docking simulation of these compounds demonstrated negative binding energies for ChEs, and BACE1, indicating high affinity and tighter binding capacity for the active site of the enzyme. Loganin was the most potent inhibitor against both ChEs and BACE1. The data suggest that these compounds together can act as a triple inhibitor of AChE, BChE, and BACE1, providing a preventive and therapeutic strategy for Alzheimer’s disease treatment.
TL;DR: A novel potent xanthine oxidase inhibitor, 3-nitrobenzoyl 9-deazaguanine (LSPN451), was selected from a series of 10 synthetic derivatives and showed a non-competitive inhibition mechanism with more affinity for the enzyme-substrate complex than for the free enzyme.
TL;DR: This is the first report of an allosteric binding site of Mtb-SK, which could largely address the selectivity issue associated with kinase inhibitors.
Abstract: Mycobacterium tuberculosis shikimate kinase (Mtb-SK) is a key enzyme involved in the biosynthesis of aromatic amino acids through the shikimate pathway. Since it is proven to be essential for the survival of the microbe and is absent from mammals, it is a promising target for anti-TB drug discovery. In this study, a combined approach of in silico similarity search and pharmacophore building using already reported inhibitors was used to screen a procured library of 20,000 compounds of the commercially available ChemBridge database. From the in silico screening, 15 hits were identified, and these hits were evaluated in vitro for Mtb-SK enzyme inhibition. Two compounds presented significant enzyme inhibition with IC50 values of 10.69 ± 0.9 and 46.22 ± 1.2 μM. The best hit was then evaluated for the in vitro mode of inhibition where it came out to be an uncompetitive and noncompetitive inhibitor with respect to shikimate (SKM) and ATP, respectively, suggesting its binding at an allosteric site. Potential bind...
TL;DR: The pharmacological properties of CX08005, a novel PTP1B inhibitor, were investigated and it was found that its inhibition is anticipated to improve insulin resistance.
Abstract: Background and purpose Insulin-sensitizing drugs are currently limited, and identifying new candidates is a challenge. Protein tyrosine phosphatase 1B (PTP1B) negatively regulates insulin signalling, and its inhibition is anticipated to improve insulin resistance. Here, the pharmacological properties of CX08005, a novel PTP1B inhibitor, were investigated. Experimental approach Recombinant hPTP1B protein was used to study enzyme activity and mode of inhibition. Docking simulation explored the interactions between CX08005 and PTP1B. Insulin sensitivity was evaluated by glucose tolerance test (GTT) in diet-induced obese (DIO) and KKAy mice; glucose-stimulated insulin secretion (GSIS), homeostasis model assessment of insulin resistance index (HOMA-IR) and whole-body insulin sensitivity (ISWB ) were also determined. A hyperinsulinaemic-euglycaemic clamp was performed to evaluate insulin-stimulated glucose disposal in both whole-body and insulin-sensitive tissues. Furthermore, CX08005's effects on muscle, fat and liver cells were determined in vitro. Key results CX08005 competitively inhibited PTP1B by binding to the catalytic P-loop through hydrogen bonds. In DIO mice, CX08005 ameliorated glucose intolerance dose-dependently (50-200 mg·kg(-1) ·day(-1) ) and decreased the HOMA-IR. In KKAy mice, CX08005 (50 mg·kg(-1) ·day(-1) ) improved glucose intolerance, GSIS, ISWB and hyperglycaemia. CX08005 also enhanced insulin-stimulated glucose disposal, increased glucose infusion rate and glucose uptake in muscle and fat in DIO mice (hyperinsulinaemic-euglycaemic clamp test). CX08005 enhanced insulin-induced glucose uptake in 3T3-L1 adipocytes and C2C12 myotubes, and increased phosphorylation of IRβ/IRS1 and downstream molecules in hepatocytes in a dose- and insulin-dependent manner respectively. Conclusions and implications Our results strongly suggest that CX08005 directly enhances insulin action in vitro and in vivo through competitive inhibition of PTP1B.
TL;DR: High catalytic activity was observed in solutions containing up to 20% ethanol, allowing the application of this enzyme in processes with high alcohol concentrations (for example beverages and biofuels) and highlights the biotechnological potential of the fungus G. butleri.
Abstract: Among the enzymes of the cellulolytic complex, β-glucosidases are noteworthy due to the possibility of their application in different industrial processes, such as production of biofuels, winemaking, and development of functional foods. This study aimed to evaluate the production and characterization of β-glucosidase from the filamentous fungus Gongronella butleri, recently isolated from Cerrado soil and cultivated in agro-industrial residue substrates. The highest production of β-glucosidase, about 215.4 U/g of dry substrate (or 21.5 U/mL), was obtained by cultivation of the microorganism on wheat bran with 55% of the initial moisture, for 96 h at 30°C. This β-glucosidase showed higher catalytic activity at pH 4.5, and a temperature of 65°C. The original enzymatic activity was recovered in a pH range of 3.0-7.5 after 24 h of incubation. The enzyme retained 80% of its catalytic activity when incubated for 1 h at 50°C. The enzyme was strongly inhibited by glucose, an effect that was completely reversed by increasing substrate concentration in the reaction mixture, which is typical for competitive inhibition. High catalytic activity was observed in solutions containing up to 20% ethanol, allowing the application of this enzyme in processes with high alcohol concentrations (for example beverages and biofuels). The significant production of β-glucosidase by the selected strain, along with these enzyme characteristics, highlights the biotechnological potential of the fungus G. butleri.
Key words: Microbial enzyme, biofuels, agro-industrial residues, cellulases, hemicellulases.
TL;DR: In this article, metal complexes of anthranilic acid derivatives that constitute a novel class of non-sugar-type α-glucosidase inhibitors were synthesized and assessed in vitro for inhibitory activity.
TL;DR: The existence of a positive feedback loop, where palmitoylation of PPT1 results in decreased activity and subsequent elevation in the amount of palMIToylated proteins, is revealed, likely to initiate a vicious cycle, which will enhance disease progression.
Abstract: Mutations in the depalmitoylating enzyme gene, PPT1, cause the infantile form of Neuronal Ceroid Lipofuscinosis (NCL), an early onset neurodegenerative disease. During recent years there have been different therapeutic attempts including enzyme replacement. Here we show that PPT1 is palmitoylated in vivo and is a substrate for two palmitoylating enzymes, DHHC3 and DHHC7. The palmitoylated protein is detected in both cell lysates and medium. The presence of PPT1 with palmitoylated signal peptide in the cell medium suggests that a subset of the protein is secreted by a nonconventional mechanism. Using a mutant form of PPT1, C6S, which was not palmitoylated, we further demonstrate that palmitoylation does not affect intracellular localization but rather that the unpalmitoylated form enhanced the depalmitoylation activity of the protein. The calculated Vmax of the enzyme was significantly affected by the palmitoylation, suggesting that the addition of a palmitate group is reminiscent of adding a noncompetitive inhibitor. Thus, we reveal the existence of a positive feedback loop, where palmitoylation of PPT1 results in decreased activity and subsequent elevation in the amount of palmitoylated proteins. This positive feedback loop is likely to initiate a vicious cycle, which will enhance disease progression. The understanding of this process may facilitate enzyme replacement strategies.
TL;DR: The cloning, overexpression and characterisation of BSH gene from a gut-associated microbe Enterococcus faecalis, and the modulating effect of the non-substrate ligand Pen V on the hydrolysing ability of EfBSH towards bile acid such as GDCA was measured showed that Pen V significantly enhanced the BSH activity.
TL;DR: Capillary electrophoresis-laser induced fluorescence (CZE-LIF) and microscale thermophoresis (MST) were used for the first time to study the inhibition of human neutrophil elastase (HNE).
TL;DR: The resulting 2-alkoxy-3-(sulfonylarylaminomethylene)-chroman-4-ones were found to be potent and selective inhibitors of ecto-5'-nucleotidase and alkaline phosphatases (TNAP and IAP).
TL;DR: The inhibitory activity of compounds against tyrosinase was improved obviously and the analysis on inhibition mechanism revealed that compound 6h might plays the role as a noncompetitive inhibitor.
TL;DR: The development of the first selective micromolar inhibitor of the UBA5 E1 enzyme that initiates UFM1 protein conjugation is described, which incorporates adenosine and zinc(II)cyclen within its core scaffold and inhibits U BA5 noncompetitively and selectively over other E1 enzymes and a panel of human kinases.
TL;DR: It is argued, that the special architecture of Cel7A with numerous subsites for binding of both substrate and product could give rise to a true noncompetitive inhibition mechanism.
Abstract: The cellobiohydrolase cellulase Cel7A is extensively utilized in industrial treatment of lignocellulosic biomass under conditions of high product concentrations, and better understanding of inhibition mechanisms appears central in attempts to improve the efficiency of this process. We have implemented an electrochemical biosensor assay for product inhibition studies of cellulases acting on their natural substrate, cellulose. Using this method we measured the hydrolytic rate of Cel7A as a function of both product (inhibitor) concentration and substrate load. This data enabled analyses along the lines of conventional enzyme kinetic theory. We found that the product cellobiose lowered the maximal rate without affecting the Michaelis constant, and this kinetic pattern could be rationalized by two fundamentally distinct molecular mechanisms. One was simple reversibility, that is, an increasing rate of the reverse reaction, lowering the net hydrolytic velocity as product concentrations increase. Strictly this is not a case of inhibition, as no catalytically inactive is formed. The other mechanism that matched the kinetic data was noncompetitive inhibition with an inhibition constant of 490 ± 40 μM. Noncompetitive inhibition implies that the inhibitor binds with comparable strength to either free enzyme or an enzymesubstrate complex, that is, that association between enzyme and substrate has no effect on the binding of the inhibitor. This mechanism is rarely observed, but we argue, that the special architecture of Cel7A with numerous subsites for binding of both substrate and product could give rise to a true noncompetitive inhibition mechanism. Biotechnol. Bioeng. 2016;113: 1178-1186. © 2015 Wiley Periodicals, Inc.
TL;DR: An amperometric biosensor was designed for the determination of sulcotrione, a β-triketone herbicide, based on inhibition of HPPD, an enzyme allowing the oxidation of hydroxyphenylpyruvate (HPP) in homogentisic acid (HGA).
TL;DR: For humans, ziram is a selective inhibitor of HSD11B2, implying that this agent may cause excessive glucocorticoid action in local tissues such as the kidney, brain, and placenta.
Abstract: Ziram is a widely used fungicide for crops. Its endocrine disrupting action is largely unknown. 11β-Hydroxysteroid dehydrogenases, isoforms 1 (HSD11B1) and 2 (HSD11B2), have been demonstrated to be the regulators of the local levels of active glucocorticoids, which have broad physiological actions. In the present study, the potency of ziram was tested for its inhibition of rat and human HSD11B1 and HSD11B2. Ziram showed the inhibition of rat HSD11B1 reductase with IC50 of 87.07 μM but no inhibition of human enzyme at 100 μM. Ziram showed the inhibition of both rat and human HSD11B2 with IC50 of 90.26 and 34.93 μM, respectively. Ziram exerted competitive inhibition of rat HSD11B1 when 11-dehydrocorticosterone was used and mixed inhibition when NADPH was supplied. Ziram exerted a noncompetitive inhibition of both rat and human HSD11B2 when steroid substrates were used and an uncompetitive inhibition when NAD(+) was supplied. Increased DTT concentrations antagonized rat and human HSD11B2 activities, suggesting that the cysteine residues are associated with the inhibition of ziram. In conclusion, for humans, ziram is a selective inhibitor of HSD11B2, implying that this agent may cause excessive glucocorticoid action in local tissues such as the kidney, brain, and placenta.
TL;DR: The results suggest that compound 20 may be an especially promising multifunctional drug for the prevention and treatment of AD.
Abstract: The aim of this study was to design new molecules and evaluate their anticholinesterase and amyloid beta (Aβ1–42) inhibition activities as multifunctional drug candidates for the treatment of Alzheimer’s disease (AD). A series of 5,6-dimethoxy-1H-indene-2-carboxamides (1–22) was synthesized; cholinesterase inhibitory activities of the compounds were measured according to Ellman’s colorimetric assay, while the thioflavin T assay was used for measuring the inhibition of Aβ1–42 aggregation. The results revealed that most compounds showed higher inhibitory activity against BuChE than AChE. Compounds 20 and 21 were found to be the most potent BuChE inhibitors with respective IC50 values of 1.08 and 1.09 μM. Compounds 16, 20, 21 and 22 exhibited remarkable inhibition of Aβ1–42 aggregation. Kinetic analysis showed that the most potent BuChE inhibitor (20) acted as a noncompetitive inhibitor. Docking studies suggested that inhibitor 20 displayed many potential hydrogen-bondings with the PAS of BuChE. Thes...
TL;DR: Javamide-II found in coffee may be a potent Sirt1/2 inhibitor, probably with potential use in some conditions of human diseases.
Abstract: Recent studies suggest that Sirt inhibition may have beneficial effects on several human diseases such as neurodegenerative diseases and cancer. Coffee is one of most popular beverages with several positive health effects. Therefore, in this paper, potential Sirt inhibitors were screened using coffee extract. First, HPLC was utilized to fractionate coffee extract, then screened using a Sirt1/2 inhibition assay. The screening led to the isolation of a potent Sirt1/2 inhibitor, whose structure was determined as javamide-II (N-caffeoyltryptophan) by NMR. For confirmation, the amide was chemically synthesized and its capacity of inhibiting Sirt1/2 was also compared with the isolated amide. Javamide-II inhibited Sirt2 (IC50; 8.7 μM) better than Sirt1(IC50; 34μM). Since javamide-II is a stronger inhibitor for Sirt2 than Sirt1. The kinetic study was performed against Sirt2. The amide exhibited noncompetitive Sirt2 inhibition against the NAD+ (Ki = 9.8 μM) and showed competitive inhibition against the peptide substrate (Ki = 5.3 μM). Also, a docking simulation showed stronger binding pose of javamide-II to Sirt2 than AGK2. In cellular levels, javamide-II was able to increase the acetylation of total lysine, cortactin and histone H3 in neuronal NG108-15 cells. In the same cells, the amide also increased the acetylation of lysine (K382) in p53, but not (K305). This study suggests that Javamide-II found in coffee may be a potent Sirt1/2 inhibitor, probably with potential use in some conditions of human diseases.
TL;DR: The kinetic and spectrometric analyses performed indicate that OA interacts with this enzyme inside a hydrophobic pocket, through an endothermic and non spontaneous process of ahydrophobic nature, which are two possible mechanisms by which OA may facilitate a better control of post-prandial hyperglycaemia and oxidative stress.
Abstract: This work investigates the role of oleanolic acid (OA), isolated from the olive ( Olea europaea L.) leaf, as a radical scavenger and inhibitor of the hydrolyzing enzymes of dietary carbohydrates. New evidence is provided showing that OA may capture 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) and peroxyl radicals, and also exert a strong and non -competitive inhibition of α-glucosidase (IC 50 10.11 ± 0.30 μM). The kinetic and spectrometric analyses performed indicate that OA interacts with this enzyme inside a hydrophobic pocket, through an endothermic and non spontaneous process of a hydrophobic nature. These are two possible mechanisms by which OA may facilitate a better control of post-prandial hyperglycaemia and oxidative stress, so contributing to preserving insulin signalling. Obesity, insulin resistance and Type 2 Diabetes Mellitus are considered the first pandemics of the 21st century. In this sense, OA might be used in future preventive and therapeutic strategies, as an ingredient in new drugs and functional foods.
TL;DR: The results demonstrated that pretreatment of the enzyme with the substrate, increased the stability of the enzymes by 21.2% during the methanolysis reaction.
Abstract: Enzymatic methanolysis reaction of canola oil utilizing Candida rugosa lipase in a solvent free system was studied in a shake flask as well as capillary channel reactors. The results demonstrated that pretreatment of the enzyme with the substrate, increased the stability of the enzyme by 21.2% during the methanolysis reaction. Performance of a capillary-channel reactor improved the yield of methanolysis up to 4-fold when compared with the shake flask experiments. Bio-kinetic constants were estimated using the Ping-Pong model by considering the competitive and non-competitive inhibition roles of methanol on enzymatic methanolysis reaction. The results of the kinetics studies showed that the enzymatic methanolysis reaction was best described by the competitive inhibition Ping-Pong model with the maximum enzyme activity of 170368 μmol min −1 g enzyme −1 , the inhibition constant of methanol 0.826 mol g enzyme −1 , the dissociation constant of canola oil 0.137 mol g enzyme −1 , and methanol dissociation constant 1.081 mol g enzyme −1 .
TL;DR: This study compared the potencies of (+)- and (-)-gossypol enantiomers in the inhibition of HSD3B1 and aromatase activities as well as progesterone and estradiol production in human placental JEG-3 cells.