Studies on the active site of rhodanese.

PROBING THE ACTIVE SITE OF RHODANESE WITH DISULFIDE REAGENTS

Biochemical properties and biological functions of the enzyme rhodanese in domestic animals

The enzyme rhodanese (thiosulfate: cyanide sulfurtransferase) is a ubiquitous enzyme and its activity ispresent in all living organisms. Many functions including cyanide detoxification, formation of iron-sulfurcenters and participation in energy metabolism have been attributed to this enzyme. The enzyme catalyzesthe transfer of a sulfur atom from sulfane containing compounds (such as thiosulfat...

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...

The rhodanese/Cdc25 phosphatase superfamily

Rhodanese domains are ubiquitous structural modules occurring in the three major evolutionary phyla. They are found as tandem repeats, with the C-terminal domain hosting the properly structured active-site Cys residue, as single domain proteins or in combination with distinct protein domains. An increasing number of reports indicate that rhodanese modules are versatile sulfur carriers that have...

Oxidative inactivation of the enzyme rhodanese by reduced nicotinamide adenine dinucleotide.

The enzyme rhodanese (thiosulfate sulfurtransferase; EC 2.8.1.1) is inactivated with a half-time of approximately 3 min when incubated with 50 mM NADH. NAD+, however, has virtually no effect on the activity. Inactivation can be prevented by the inclusion of the substrate thiosulfate. The concentration of thiosulfate giving half-protection is 0.038 mM. In addition, NADH, but not NAD+, is a compe...