The effect of beta-bromopyruvic acid on fructose-1, 6-diphosphate aldolase from rabbit muscle.

Rabbit muscle aldolase (RMA) is 96 per cent inhibited in the presence of beta-bromopyruvic acid (BPA) in a molar ratio of 1/250, during 60 minutes incubation. The chemical reaction of higher significance in this phenomenon is the alkylation of -SHgroups of both apparent and buried types, with formation of S-pyruvil-cystein. The previous treatment of the enzyme with FDP protects aldolase, decreasing the rate of inhinition by BPA to about 56 per cent. FDP protection of the enzyme protects nearly 5-SH groups against the alkylating effect of BPA. Cyanogen bromide hydrolysis of the carboxymethylated protein results in the classical formation of 4 fragments, peptides F1, the NH-2terminal; F2, the COOH-terminal; F3, the active site containing peptide; and F4, a small peptide located between F2 F3. The protection bestowed upon the enzyme by FDP, against the alkylating effect of BPA, is located in the F1, F2, and F3 either in BPA treated aldolases or in the BPA treated FDP-aldolase. Part of the inhibiting effect of BPA is then attributed to the possible interaction between this compound and the basic aminoacids in the aldolase molecule.