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Regulation of catalytic activity of a multifunctional polyketide biosynthetic enzyme, 6-hydroxymellein synthase, by interaction between NADPH and phenylglyoxal-sensitive amino acid residue at the reaction center.
- Source :
-
Biochimica et biophysica acta [Biochim Biophys Acta] 2001 Sep 10; Vol. 1549 (1), pp. 51-60. - Publication Year :
- 2001
-
Abstract
- Treatment of 6-hydroxymellein synthase, a multifunctional polyketide biosynthetic enzyme in carrot cells, with phenylglyoxal yielded a chemically modified protein in which approximately two moles of the reagent were covalently attached to each subunit of the enzyme. Only NADH- but not NADPH-associated form of native 6-hydroxymellein synthase was inhibited by cerulenin; however, the NADPH-synthase complex lost the insensitivity by the chemical modification of the enzyme protein with phenylglyoxal. Appreciable differences in K(m) values observed between the NADPH- and NADH-associated enzymes were greatly reduced by the treatment with phenylglyoxal. Although the catalytic activity of the NADPH-associated synthase was enhanced by the addition of free CoA, the compound exhibited a significant inhibitory activity to the phenylglyoxal-modified enzyme. A marked deuterium isotope effect in the catalytic reaction of the native synthase-NADPH complex was appreciably decreased in the chemically modified enzyme. These results strongly suggest that an electrostatic interaction between the phosphate group attached to the 2'-position of adenosyl moiety of NADPH and the phenylglyoxal-sensitive amino acid residue, probably arginine, at the reaction center of 6-hydroxymellein synthase regulates several biochemical properties of this multifunctional enzyme.
- Subjects :
- Acyltransferases antagonists & inhibitors
Catalysis drug effects
Cerulenin pharmacology
Coenzyme A pharmacology
Dose-Response Relationship, Drug
Kinetics
Ligases antagonists & inhibitors
Models, Chemical
Multienzyme Complexes antagonists & inhibitors
Oxidoreductases antagonists & inhibitors
Phenylglyoxal pharmacology
Acyltransferases chemistry
Enzyme Inhibitors pharmacology
Ligases chemistry
Multienzyme Complexes chemistry
NADP chemistry
Oxidoreductases chemistry
Phenylglyoxal chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 0006-3002
- Volume :
- 1549
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Biochimica et biophysica acta
- Publication Type :
- Academic Journal
- Accession number :
- 11566368
- Full Text :
- https://doi.org/10.1016/s0167-4838(01)00243-6