In vitro effect of cyanide, thiosulphate and S-adenosyl- l-methionine on the activity of rhodanese and other enzymes

Abstract

1. 1. Some in vitro studies were performed to elucidate the action of S-adenosyl- l-methionine (SAM) and thiosulphate on liver rhodanese, δ-amino-levulinic acid dehydratase (ALA-D) and cytochrome oxidase affected by cyanide in the experimental conditions. 2. 2. SAM was unable to interact with the sulfur substituted rhodanese complex suggesting that SAM would blockade the thiosulphate binding sites on rhodanese. 3. 3. Cyanide and thiosulphate inhibited ALA-D activity when both compounds were present in the incubation or the preincubation mixture. Cyanide binding on the enzyme was irreversible. 4. 4. Cyanide inhibited cytochrome oxidase activity and the reversible nature of the binding was demonstrated by gel filtration. 5. 5. SAM had no effect on either ALA-D or cytochrome oxidase activities.