The biosynthesis of cyanogenic glucosides in higher plants. N-Hydroxytyrosine as an intermediate in the biosynthesis of dhurrin by Sorghum bicolor (Linn) Moench

Møller, B.L. and Conn, E.E. (1979) The biosynthesis of cyanogenic glucosides in higher plants. N-Hydroxytyrosine as an intermediate in the biosynthesis of dhurrin by Sorghum bicolor (Linn) Moench. Journal of Biological Chemistry, 254 (17). pp. 8575-8583.

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Abstract

The following compounds were tested as early intermediates in the conversion of tyrosine to p-hydroxymandelonitrile by a microsomal preparation from dark grown sorghum seedlings: p-hydroxyphenylacetamide, 1-nitro-2-p-hydroxyphenylethane, p-hydroxyphenyl-pyruvic acid oxime, tyramine, N-hydroxytyramine, and N-hydroxytyrosine. Of these, only N-hydroxytyrosine was metabolized to p-hydroxymandelonitrile. N-Hydroxytyrosine was produced from L-[U-14C]tyrosine in tracer experiments when unlabeled N-hydroxytyrosine was added as a trap. These data indicate N-hydroxytyrosine as the first intermediate in the biosynthesis of dhurrin, the cyanogenic glucoside of sorghum, and represent the first demonstration of the formation of an alpha-N-hydroxy-amino acid in a biological system. The enzyme system involved in this reaction was partially characterized with respect to substrate specificity and the effect of various inhibitors. The enzyme was shown to have properties different than those reported for the mammalian enzyme system(s) involved in the N-hydroxylation of amine drugs. The possible involvement of N-hydroxyamino acids in the biosynthesis of other secondary plant products is discussed

Item Type: Article
Author Affiliation: Department of Biochemistry and Biophysics, University of California, Davis, California 95616
Subjects: Crop Improvement
Divisions: Sorghum
Depositing User: Ms K Syamalamba
Date Deposited: 09 Oct 2012 08:25
Last Modified: 09 Oct 2012 08:25
Official URL: http://www.jbc.org/content/254/17/8575.abstract
URI: http://eprints.icrisat.ac.in/id/eprint/8332

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