Purification and properties of a stilbene synthase from induced cell suspension cultures of peanut.
Stilbene synthase ( resveratrol -forming) converts one molecule of rho- coumaroyl -CoA and three molecules of malonyl-CoA into 3,4',5- trihydroxystilbene . Following selective induction of stilbene synthesis in cell suspension cultures of peanut (Arachis hypogaea), the enzyme was extracted and purified to apparent homogeneity by chromatography on DEAE-cellulose and hydroxylapatite. The enzyme was found to be a dimer of estimated Mr = 90,000 exhibiting under denaturing conditions a subunit Mr of approximately 45,000. The isoelectric point was determined with pI = 4.8. The enzyme's high selectivity towards rho- coumaroyl -CoA (Km = 2 microM) as substrate qualified it as resveratrol -forming stilbene synthase. Structurally related CoA esters, e.g. dihydro-rho- coumaroyl -CoA and cinnamoyl-CoA, were converted less than 1/10 as efficiently as rho- coumaroyl -CoA. Malonyl-CoA (Km = 10 microM) could not be substituted by acetyl-CoA. The purified enzyme was free of chalcone synthase activity. Antibodies raised against stilbene synthase were shown to be monospecific and not to cross-react with chalcone synthase.
D000217:Acyltransferases / Q000032:analysis; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D010367:Arachis; D002950:Citrate (si)-Synthase / Q000032:analysis; D003429:Cross Reactions; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D008291:Malate Dehydrogenase / Q000032:analysis; D008970:Molecular Weight; D010944:Plants / Q000201:enzymology*; D013267:Stilbenes / Q000096:biosynthesis* / Q000302:isolation & purification; D013552:Swine
D000911:Antibodies, Monoclonal; D013267:Stilbenes; D008291:Malate Dehydrogenase; D000217:Acyltransferases; C022674:stilbene synthase; C020141:flavanone synthetase; D002950:Citrate (si)-Synthase