[Sulfhydryl groups of L-asparaginase A from Pseudomonas fluorescens AG].
It has been demonstrated that the activity of asparaginase A from Ps. fluorescens AG is completely inhibited by 10(-4) M p-chloromercurybenzoate and by 70-85% by Zn2+, Ca2+ and Cu2+ (2.10(-2) M). Iodoacetate, iodoacetamide, N-ethylimide of maleic acid and 5,5'-dithiobis-(2-nitrobenzoic acid) do not decrease the enzyme activity. Dithiothreitol and beta-mercaptoethanol reactivate the enzyme. L-asparagine, the substrate of asparaginase, protects the enzyme in a large degree against the inhibitory action of p-chloromercurybenzoate. p-chloromercurybenzoate induces a sharp increase in the asparaginase inactivation rate at acidic (6.5--5.5) and alkaline (7.5-8.5) values of pH. The enzyme modification by p-chloromercurybenzoate does not change the Km value for L-asparagine, but decreases Vmax. Thus it may be assumed, that asparaginase from Ps. fluorescens AG contains sulfhydryl groups essential for the enzyme activity.
D001215:Asparaginase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011551:Pseudomonas fluorescens / Q000201:enzymology*; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; D001215:Asparaginase
Sul'fgidril'nye gruppy L-asparaginazy A iz Pseudomonal fluorescens Ag