|
type |
Journal Article |
authors |
Satoh, S.; Yang, S. F. |
title |
Specificity of S-adenosyl-L-methionine in the inactivation and the labeling of 1-aminocyclopropane-1-carboxylate synthase isolated from tomato fruits |
journal |
Arch Biochem Biophys |
Activity |
4.4.1.14 |
Family |
4.4.1.14 |
ui |
Samilac |
year |
(1989) |
volume |
271 |
number |
1 |
pages |
107-12 |
| |
keywords |
Catalysis |
abstract |
1-Aminocyclopropane-1-carboxylate (ACC) synthase, which catalyzes the conversion of S-adenosyl-L-methionine (AdoMet) to ACC, is irreversibly inactivated by its substrate AdoMet. AdoMet has two diastereomers with respect to its sulfonium center, (-)-AdoMet and (+)-AdoMet. We prepared (+)- and (-)-AdoMet from a commercial source, and compared their activities as a substrate and as an inactivator of ACC synthase isolated from tomato (Lycopersicon esculentum Mill). fruits. Only (-)-AdoMet produced ACC, whereas both (-)- and (+)-AdoMet inactivated ACC synthase; (+)-AdoMet inactivated the enzyme three times faster than (-)-AdoMet. We have previously shown that ACC synthase was specifically radiolabeled when the enzyme was incubated with S-adenosyl-L-[3,4-14C]methionine. The present results further indicate that S-adenosyl-L-[carboxyl-14C]methionine, but not S-adenosyl-L-[methyl-14C]methionine, radiolabeled the enzyme. These data suggest that the 2-aminobutyric acid portion of AdoMet is linked to ACC synthase during the autoinactivation process. A possible mechanism for ACC synthase inactivation by AdoMet is discussed. |
last changed |
2008/04/25 17:36 |
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