Effect of epsilon-aminocaproyl-S-benzyl-L-cysteine on the activity of plasminogen activators.
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The effect of epsilon-aminocaproyl-S-benzyl-L-cysteine on the activation of plasminogen by t-PA. streptokinase and urokinase has been examined using fibrinolytic method. The obtained results have been compared with the obtained results for epsilon-aminocaproic acid and trans-4-(aminomethyl)cyclohexanecarboxylic acid. The inhibition of the plasminogen activation determined with the use of epsilon-aminocaproyl-S-benzyl-L-cysteine was weaker than the inhibition determined by using antifibrinolytic aminoacids. (+info)
Chemistry of the inactivation of 4-aminobutyrate aminotransferase by the antiepileptic drug vigabatrin.
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The chemical modification of pig liver 4-aminobutyrate aminotransferase by the antiepileptic drug 4-aminohex-5-enoate (Vigabatrin) has been studied. After inactivation by 14C-labeled Vigabatrin, the enzyme was digested with trypsin, and automated Edman degradation of the purified labeled peptide gave the sequence FWAHEHWGLDDPADVMTFSKK. Chymotryptic digestion of the tryptic peptide and sequencing of a resulting tripeptide identified the penultimate lysine residue of this peptide as the site of covalent modification. This lysine normally binds the coenzyme. Absorption spectroscopy demonstrated the absence of coenzyme from the tryptic peptide, and mass spectrometry showed its mass/charge ratio to be increased by 128. All of the bound coenzyme released after denaturation of the inactivated enzyme was as pyridoxamine phosphate. The structural nature of the modification is deduced, and mechanisms for its occurrence identified. Initially, 1 mol of radiolabeled inhibitor was bound per mol of monomer of the enzyme, although approximately half was released during denaturation and digestion, while the remainder was irreversibly bound. Coenzyme not released as pyridoxamine phosphate retained the absorbance characteristics of the aldimine, although the enzyme was completely inactive. Mass spectrometry of the sample of purified radiolabeled tryptic peptide revealed the presence of an approximately equal amount of a second fragment that contained no modification and from which the second lysine was absent, indicating that at the time of proteolysis the active site lysine was unaltered in 50% of the enzyme molecules. (+info)
Arginase inhibition restores NOS coupling and reverses endothelial dysfunction and vascular stiffness in old rats.
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Novel yellow compounds, dilysyldipyrrolones A and B, formed from xylose and lysine by the Maillard reaction.
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When a solution containing xylose and L-lysine is heated under weakly acidic conditions, it turns brown by the Maillard reaction. We isolated here two novel yellow compounds from a heated solution containing xylose and lysine, and identified pyrrolyl-methylidene-pyrrolone derivatives named dilysyldipyrrolones A and B. Their chemical structures were elucidated by instrumental analyses as 6-[[1-[(S)-5-amino-1-carboxypentyl]-3-hydroxy-pyrrol-2-yl]-(E)-2-methylidene-5-me thyl-1,2H-pyrrol-3-one-1-ly]-(S)-2-amino-hexanoic acid (dilysyldipyrrolone A) and 6-[[1-[(S)-5-amino-5-carboxypentyl]-3-hydroxy-pyrrol-2-yl]-(E)-2-methylidene-5-me thyl-1,2H-pyrrol-3-one-1-yl]-(S)-2-amino-hexanoic acid (dilysyldipyrrolone B). These were the major pigments in the heated solution. (+info)
Structure of the heme biosynthetic Pseudomonas aeruginosa porphobilinogen synthase in complex with the antibiotic alaremycin.
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