S-adenosylhomocysteine metabolism in various species.

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Walker RD, Duerre JA

S-adenosylhomocysteine metabolism in various species.

Can J Biochem. 1975 Mar;53(3):312-9.

PubMed ID

1125818 [ View in PubMed

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Abstract

Eleven microorganisms, four plants, and major organs from the chicken, dog, rat and rabbit were assayed for the presence of S-adenosylhomocysteine hydrolase, S-adenosylhomocysteine nucleosidase, and S-ribosylhomocysteine-cleavage enzyme. All bacteria (procaryotes) were found to possess S-adenosylhomocysteine nucleosidase and S-ribosylhomocysteine-cleavage enzyme but not S-adenosylhomocysteine hydrolase; All eucaryotes tested, including yeasts, plants, birds, and mammals, possessed S-adenosylhomocysteine hydrolase but not S-adenosylhomocysteine nucleosidase or S-ribosylhomocysteine-cleavage enzyme. Of all the organs assayed in the vertebrates, the level of S-adenosylhomocysteine hydrolase was highest in liver, pancreas, and kidney, lower spleen and testis, and very low in brain and heart; In all systems tested, equilibrium of the hydrolase reaction always favored synthesis over hydrolysis. We studied some of the kinetic properties of the hydrolase from rat liver; In the direction of synthesis, the Km value was 1.5 mM for adenosine and 4.5 mM for L-homocysteine, whereas marked substrate inhibition was observed with L-homocysteine. The condensation reaction is subject to product inhibition, and was inhibited by adenine. Results from in-vivo experiments revealed that the cells of the various organs of the dog are impermeable to the exogenously administered S-adenosylhomocysteine.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Adenine	5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase	Protein	Escherichia coli (strain K12)	Unknown	Not Available	Details