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Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Seseli taxa are widely known as a traditional medicinal herb, and S. resinosum collected from stony and rocky areas is endemic to the flora of Turkey. In this study, to reveal the plant's pharmacological importance, its ability to inhibit some medicinal enzymes was examined, assisted by molecular docking studies and phytochemical component analysis. The IC50 values for studied enzymes were calculated between 0.434 - 92.81 μg/mL, and the extract has lower inhibitory concentrations against α-glucosidase, α-amylase, and HMG_CoA reductase involved in carbohydrate and cholesterol metabolism. In addition, reverse-phase HPLC analysis was performed to correlate the enzyme inhibition ability with phenolic compositions. Benzoic acid and methyl chavicol were detected as the most abundant ingredients with the amount of 204.50±2.23 and 93.18±1.01 μg g-1, respectively. TPC and TFC of the extract were founded at 31.23 ± 0.56 GAE/g and 5.54 ± 0.11 QE/g, respectively. The extract showed inhibitory and lethal effects, especially against all tested gram-negative strains at 7.5 and 15 mg mL-1, respectively. In conclusion, the present study demonstrated that S. resinosum extract harbors bioactive compounds with inhibitory properties such as benzoic acid and catechin. It is expected that these primary data on the S. resinosum may contribute to building new experimental studies to open new avenues for research to support the pharmacological effects. [ABSTRACT FROM AUTHOR]

Thiamine is an essential cofactor that is required for processes of general metabolism amongst all organisms, and it is likely to have played a role in the earliest stages of the evolution of life. Here, we review from a structural perspective the enzymatic mechanisms that involve this cofactor. We explore asymmetry within homodimeric thiamine diphosphate (ThDP)-dependent enzyme structures and discuss how this may be correlated with the kinetic properties of half-of-the-sites reactivity, and negative cooperativity. It is likely these structural and kinetic hallmarks may arise through reciprocal coupling of active sites. This mode of communication between distant active sites is not unique to ThDP-dependent enzymes, but is widespread in other classes of oligomeric enzyme. Thus, it appears likely to be a general phenomenon reflecting a powerful mechanism of accelerating the rate of a chemical pathway. Finally, we speculate on the early evolutionary history of the cofactor and its ancient association with protein and RNA. [ABSTRACT FROM AUTHOR]

The crystal structure of Escherichia coli ketopantoate reductase in complex with 2′-monophosphoadenosine 5′-diphosphoribose, a fragment of NADP+ that lacks the nicotinamide ring, is reported. The ligand is bound at the enzyme active site in the opposite orientation to that observed for NADP+, with the adenine ring occupying the lipophilic nicotinamide pocket. Isothermal titration calorimetry with R31A and N98A mutants of the enzyme is used to show that the unusual `reversed binding mode' observed in the crystal is triggered by changes in the protonation of binding groups at low pH. This research has important implications for fragment-based approaches to drug design, namely that the crystallization conditions and the chemical modification of ligands can have unexpected effects on the binding modes. [ABSTRACT FROM AUTHOR]

An easy and rapid method for the purification of a bacteriolytic endopeptidase produced by Myxococcus virescens is described. The bacteria were grown in casitone media and the cells were sedimented by centrifugation. About 1.2 g of montmorillonite were added per liter of cell-free culture solution. The clay was sedimented by centrifugation and the enzyme was then eluted by 0.05 M Na-phosphate buffer pH 6.0, containing 0.4 M NaCl. The enzyme was diluted with water and chromatographed on carboxymethyl-cellulose columns. The purified enzyme liberated free amino groups but no reducing sugars or N-acetylhexosamines when acting on purified N-acetylated cell wall of Micrococcus lysodeikticus. Analysis of N- and C-terminal amino acids in the digestion products showed that the enzyme had liberated about 110 nmoles of lysine ε-amino groups and 60 nmoles of alanine carboxyl groups per mg of cell wall. When it acted on a bisdisaccharide pentapeptide dimmer isolated from M. lysodeikticus cell walls, it cleaved about 30% of the alanyl-lysine linkages. Consequently the enzyme was and alanyl-lysine endopeptidase. It had no muramyl-alanine amidase activity. [ABSTRACT FROM AUTHOR]

Pigeon liver malic enzyme was chemically attached to Sepharose 4B-CL beads. The enzyme lost ≈ 50% of its original activity when immobilization was carried out with 5 mg CNBr/ml gel. Immobilization performed at pH 8.0 or pH 4.5 resulted in the formation of matrix-bound tetramer and monomer, respectively. Matrix-bound reconstituted tetramer was derived from matrix-bound monomer by mixing the latter with soluble enzyme at pH 4.5, then raised the pH of the solution to 8.0. The matrix-bound monomer was demonstrated to be enzymically fully active in terms of specific activity. The pH profile for the enzymic reaction was similar for both soluble and immobilized enzymes. However, the latter had a broader range for the optimum pH (pH 6.8-7.8). The Arrhenius plots for all immobilized enzyme forms were biphasic with inflection at ≈ 27°C. The apparent Michaelis constants for the substrates increased about 2-3-fold after immobilization. All immobilized enzyme forms, including the matrix-bound monomer, showed substrate inhibition at high concentrations of L-malate. Both high-affinity and low-affinity binding sites for Mn[sub2+] existed for all immobilized enzyme forms. These results are consistent with an existing asymmetric model, but are not compatible with a sequential model for the enzyme tetramer. The immobilized enzyme was stable for at least four months at 4°C. As compared to soluble enzyme, the immobilized enzyme was less inhibited by (NH[sub4])[sub2]SO[sub4] or NaCl. It was also resistant to inactivation with periodate-oxidized aminopyridine adenine dinucleotide phosphate, an affinity label for malic enzyme. Incubation of the immobilized enzyme (1.25 μM) with the reagent (5.6 mM) resulted in pseudo-first-order inactivation with a rate constant of 0.0108 min[sup-1] that was at least an order of magnitude smaller than that for the soluble enzyme. [ABSTRACT FROM AUTHOR]

A protease has been isolated from germinated sorghum seeds in a highly purified, crystalline form. A molecular weight of about 80000 has been obtained for the enzyme from gel filtration experiments. The protease does not require serine or cysteine (sulfhydryl) at the active site and has no requirement, for metal ions. This enzyme has been classified as an "acid protease", since it has it's pH optimum at acidic pH range (pH 3.6). Effects of enzyme concentration and substrafe concentration on the rate of catalysis have been studied and an apparent K1 of 0.76 mM and 0.19 mM has been obtained against bovine serum albumin and N,N-dimethyl albumin as substrates, respectively. [ABSTRACT FROM AUTHOR]