Inactivation of S-adenosyl-L-homocysteine hydrolase by cAMP results from dissociation of enzyme-bound NAD+.
AUTOR(ES)
Hohman, R J
RESUMO
S-Adenosyl-L-homocysteine hydrolase (EC 3.3.1.1) is inactivated by cAMP and also by 2'-deoxyadenosine, and in both cases, activity is restored by incubating the inactivated enzyme with NAD+. We have previously presented evidence that, despite these similarities, inactivation by these two ligands proceeds by different mechanisms. We have now used a fluorescence technique to quantitate enzyme-bound NAD+ and NADH on S-adenosyl-L-homocysteine hydrolase from Dictyostelium discoideum, and we have confirmed that cAMP and 2'-deoxyadenosine inactivate by different mechanisms. Whereas inactivation by 2'-deoxyadenosine is due to reduction of the enzyme-bound NAD+ to NADH, incubation of S-adenosyl-L-homocysteine hydrolase with cAMP results in dissociation of the enzyme-bound NAD+. The dissociation is reversible, and reactivation likely occurs by restoration of the initial NAD+ content. This reversible inactivation by cAMP may be a mechanism of controlling biological methylation reactions by adjusting intracellular concentrations of S-adenosyl-L-homocysteine through action of S-adenosyl-L-homocysteine hydrolase.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=390428Documentos Relacionados
- cDNA for S-adenosyl-L-homocysteine hydrolase from Catharanthus roseus.
- Mutational and nucleotide sequence analysis of S-adenosyl-L-homocysteine hydrolase from Rhodobacter capsulatus.
- Amino acid sequence of S-adenosyl-L-homocysteine hydrolase from rat liver as derived from the cDNA sequence.
- Purification, crystallization and preliminary crystallographic studies of plant S-adenosyl-l-homocysteine hydrolase (Lupinus luteus)
- Induction by fungal elicitor of S-adenosyl-L-methionine synthetase and S-adenosyl-L-homocysteine hydrolase mRNAs in cultured cells and leaves of Petroselinum crispum.
