S-Adenosylmethionine-Dependent Inactivation and Radiolabeling of 1-Aminocyclopropane-1-Carboxylate Synthase Isolated from Tomato Fruits 1
AUTOR(ES)
Satoh, Shigeru
RESUMO
1-Aminocyclopropane-1-carboxylic acid (ACC) synthase was partially purified from the homogenate of wounded tomato (Lycoperiscon esculentum Mill.) pericarp tissue by (NH4)2SO4 fractionation followed by conventional column chromatography with diethylaminoethyl-Sepharose, Sephadex G-150, Affi-Gel blue and hydroxylapatite. The partially purified ACC synthase preparation attained a specific activity of about 12,000 nmoles per hour per milligram protein. Employing this enzyme preparation, we confirmed that the ACC synthase was inactivated by its substrate, S-adenosyl-l-methionine (SAM), during its catalytic action. When the partially purified enzyme preparation was incubated with [3,4-14C]SAM and the resulting proteins were analyzed by sodium dodecyl sulfate-gel electrophoresis, only one radioactive protein band was observed. This protein was thought to be ACC synthase based on its molecular mass of 50 kD and on the fact that it was specifically bound to a monoclonal antibody against ACC synthase (AB Bleecker et al. 1986 Proc Natl Acad Sci USA 83, 7755-7759). These results suggest that the substrate SAM acts as an enzyme-activated inactivator of ACC synthase by covalently linking a fragment of SAM molecule to the active site of ACC synthase, resulting in the inactivation of the enzyme.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1055533Documentos Relacionados
- Differential expression of two genes for 1-aminocyclopropane-1-carboxylate synthase in tomato fruits.
- Nucleotide sequence of a cDNA for 1-aminocyclopropane-1-carboxylate synthase from melon fruits.
- Differential Expression and Internal Feedback Regulation of 1-Aminocyclopropane-1-Carboxylate Synthase, 1-Aminocyclopropane-1-Carboxylate Oxidase, and Ethylene Receptor Genes in Tomato Fruit during Development and Ripening1
- Cloning and sequence of two different cDNAs encoding 1-aminocyclopropane-1-carboxylate synthase in tomato.
- Differential accumulation of transcripts for four tomato 1-aminocyclopropane-1-carboxylate synthase homologs under various conditions.