Studies on the Active Site of Rhodanese

Studies on the active site of rhodanese.

The complete loss of enzymic activity on reaction with alkylating agents, aromatic nitro compounds, or aliphatic mercaptans indicates the importance of sulfhydryl groups for catalysis. Analyses during the course of inactivation with any of these reagents revealed the loss of one of the two -SH groups in the rhodanese monomer when inactivation was complete. Amino acid analysis of iodoacetate-ina...

PROBING THE ACTIVE SITE OF RHODANESE WITH DISULFIDE REAGENTS

probing the active site of rhodanese with disulfide reagents

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Active site structural features for chemically modified forms of rhodanese.

In the course of the reaction catalyzed by rhodanese, the enzyme cycles between two catalytic intermediates, the sulfur-free and the sulfur-substituted (persulfide-containing) forms. The crystal structure of sulfur-free rhodanese, which was prepared in solution and then crystallized, is highly similar to that of sulfur-substituted enzyme. The inactivation of sulfur-free rhodanese with a small m...

Studies on the Active Site of Clostripain

Clostripain is rapidly and selectively inactivated by the chloromethyl ketone derived from cr-N-tosyl-L-lysine (TLCK) with an apparent second order rate constant of 8.7 X lo4 M-I set-i at pH 6.5. Alkylation by TLCK occurs only with catalytically active enzyme, the rate of which is considerably retarded by the competitive inhibitors, oc-Ntosyl-L-homoarginine methyl ester and benzamidine. In cont...