Chemical modification by 2,4,6-trinitrobenzenesulfonic acid (TNBS) of an essential amino group in 3-ketovalidoxylamine A C-N lyase.
3-Ketovalidoxylamine A C-N lyase of Flavobacterium saccharophilum is a monomeric protein with a molecular weight of 36000, and contains 32 amino groups and no cysteine or cystine residues. The enzyme was inactivated by 2,4,6-trinitrobenzenesulfonic acid (TNBS) following pseudo-first order kinetics. Substrate of the lyase, p-nitrophenyl-3-ketovalidamine, protected the enzyme against the inactivation, suggesting that the modification occurred at or near the active site. Although several amino groups were modified by TNBS, a plot of log (reciprocal of the half-time of inactivation) versus log (concentration of TNBS) suggested that one amino group has an essential role in catalysis.
Department of Biochemistry, School of Pharmacy, Hokuriku University, Ishikawa, Japan.
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Takeuchi
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Neyazaki
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Matsui
D000596:Amino Acids / Q000032:analysis*; D019759:Carbon-Nitrogen Lyases; D055598:Chemical Phenomena; D002621:Chemistry; D002942:Circular Dichroism; D007700:Kinetics; D008190:Lyases / Q000032:analysis / Q000037:antagonists & inhibitors*; D009578:Nitrobenzenes / Q000494:pharmacology*; D014302:Trinitrobenzenesulfonic Acid / Q000494:pharmacology*
D000596:Amino Acids; D009578:Nitrobenzenes; D014302:Trinitrobenzenesulfonic Acid; D008190:Lyases; D019759:Carbon-Nitrogen Lyases; C048147:3-ketovalidoxylamine A C-N lyase