Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P30044 (antioxidant enzyme)
 8,037 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Selenosubtilisin, a semisynthetic enzyme produced by chemical modification of subtilisin's catalytic serine, mimics the antioxidant enzyme glutathione peroxidase, catalyzing the reduction of hydroperoxides by 3-carboxy-4-nitrobenzenethiol. In analogy with the unmodified protease, selenosubtilisins derived from distantly related subtilisin templates exhibit significantly different kinetic properties. Selenosubtilisin BPN' not only is less active than the previously studied Carlsberg selenoenzyme but exhibits sequential rather than ping-pong kinetics, indicating the formation of a ternary complex between enzyme, thiol, and peroxide prior to product release. Experiments with subtilisin E and the BPN' Y217L variant show that the observed differences in kinetic mechanism and chemical efficiency can be attributed largely to amino acid substitutions in the enzyme's S1 and S1' binding sites, respectively. These contributions appear to be roughly additive, and a BPN' triple mutant (E156S/G169A/Y217L) has properties that closely approximate those of selenosubtilisin Carlsberg. The kinetic mechanism of selenosubtilisin can thus be controlled by limited mutagenesis of several active site residues not directly involved in the redox chemistry.
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PMID:Nonessential active site residues modulate selenosubtilisin's kinetic mechanism. 775 93

Selenosubtilisin, a semisynthetic enzyme produced by chemical modification of subtilisin's catalytic serine, mimics the antioxidant enzyme glutathione peroxidase, catalyzing the reduction of hydroperoxides by 3-carboxy-4-nitrobenzenethiol. In analogy with the natural peroxidase, a variety of hydroperoxides are accepted as substrates for the semisynthetic enzyme, whereas the dialkyl compound tert-butyl peroxide is not. Kinetic investigations reveal that kmax is dependent upon the nature of the hydroperoxide, indicating that peroxide-mediated oxidation of the enzymic selenolate is at least partially rate-limiting. Experiments with the radical trap 2,6-di-tert-butyl-4-methylphenol suggest that, while the nonenzymic reaction between tert-butyl hydroperoxide and thiol involves free radicals, the same reaction catalyzed by selenosubtilisin does not. The studies described here support the enzyme's proposed ping-pong mechanism and are consistent with previous mechanistic observations.
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PMID:Peroxide dependence of the semisynthetic enzyme selenosubtilisin. 826 74

Pleurotus geesteranus is a promising source of bioactive compounds. However, knowledge of the antioxidant behaviors of P. geesteranus protein hydrolysates (PGPHs) is limited. In this study, PGPHs were prepared with papain, alcalase, flavourzyme, pepsin, and pancreatin, respectively. The antioxidant properties and cytoprotective effects against oxidative stress of PGPHs were investigated using different chemical assays and H2O2 damaged PC12 cells, respectively. The results showed that PGPHs exhibited superior antioxidant activity. Especially, hydrolysate generated by alcalase displayed the strongest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (91.62%), 2,2-azino-bis (3-ethylbenzothia zoline-6-sulfonic acid) (ABTS) radical scavenging activity (90.53%), ferric reducing antioxidant power, and metal ion-chelating activity (82.16%). Analysis of amino acid composition revealed that this hydrolysate was rich in hydrophobic, negatively charged, and aromatic amino acids, contributing to its superior antioxidant properties. Additionally, alcalase hydrolysate showed cytoprotective effects on H2O2-induced oxidative stress in PC12 cells via diminishing intracellular reactive oxygen species (ROS) accumulation by stimulating antioxidant enzyme activities. Taken together, alcalase hydrolysate of P. geesteranus protein can be used as beneficial ingredients with antioxidant properties and protective effects against ROS-mediated oxidative stress.
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PMID:Preparation of Antioxidant Protein Hydrolysates from Pleurotus geesteranus and Their Protective Effects on H2O2 Oxidative Damaged PC12 Cells. 3322 51