Zeatin 9-acetylation

This enzyme ]EC 4.2.99.13], also known as lupinic acid synthase, catalyzes the reaction of O-acetyl-L-serine with zeatin to produce lupinate and acetate. Zeatin is N -(4-hydroxy-3-methyl-butyl-iran5 -2-enylamino)purine. A number of other A -substituted purines can function as substrates for this enzyme. 

Cytokinin specificity is determined by the structure of its side chain, where even a small modification can significantly affects the biological activity. Among enzymatic modifications that have been already proved in vivo are ranked O-glycosylation and O-acetylation of zeatin, cisJtrans isomerization of its hydroxyl group, double bond reduction to dihydrozeatin and hydroxylation of A -isopentenyl moiety of isopentenyladenine type to zeatin-types of cytokinins. 

Enzymic acetylation of thymidine and deoxyuridine using vinyl acetate and an engineered mutant of subtilisin gives the S -(9-acetyl derivatives specifically,247 whilst the lipase from Candida cylindraceae catalyses the selective hydrolysis of the 3 -0-acetyl group of 3, 5 -di-0-acetylthymidine. Use of porcine pancreatic lipase, on the other hand, selectively hydrolyses the 5 -0-acetyl group.248 Selective enzymic acetylation at 0-5 has also been reported for zeatin 2 -deoxyriboside.249... 

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