Vicianin Hydrolase is a Novel Cyanogenic  -Glycosidase Specific to  -Vicianoside (6-O- -L-Arabinopyranosyl- -D-Glucopyranoside) in Seeds of Vicia angustifolia

• Published in: Plant and cell physiology 2007-07, Vol.48 (7), p.938-947
• Main Authors: Ahn, Young Ock, Saino, Hiromichi, Mizutani, Masaharu, Shimizu, Bun-ichi, Sakata, Kanzo
• Format: Article
• Language: English
• Subjects: Baculovirus; Vicia angustifolia
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcm065

The cyanogenic disaccharide glycoside, vicianin [mandelonitrile β -vicianoside (6-O -α -l-arabinopyranosyl-β -d-glucopyranoside)], is accumulated in seeds of Vicia angustifolia var. segetalis . Vicianin hydrolase (VH) catalyzes the hydrolysis of vicianin into mandelonitrile and a disaccharide vicianose. VH was purified from the seeds using DEAE-, CM- and Con A-Sepharose chromatography, and the molecular mass of the purified VH was estimated to be 56 kDa on SDS-PAGE. The N-terminal amino acid sequence of the purified VH was determined, and a cDNA encoding VH was obtained. The deduced VH protein consists of a 509 amino acid polypeptide containing a putative secretion signal peptide. It shares about 50% identity with various kinds of plant β -glycosidases including tea leaf β -primeverosidase and furcatin hydrolase, and is classified in family 1 of the glycosyl hydrolases. The VH transcript was detected abundantly in seeds and moderately in flowers, but only slightly in leaves, stems and roots, indicating that the organ distribution of VH expression is similar to that of the substrate vicianin. The recombinant VH was produced in insect cells with a baculovirus system, and was compared with the native VH in terms of substrate specificity. Both enzymes hydrolyzed vicianin to release vicianose, demonstrating that VH is a disaccharide-specific β -glycosidase. VH also hydrolyzed the mandelonitrile β -glucoside prunasin to some extent but did not hydrolyze the gentiobioside amygdalin, both of which contain the same aglycone as vicianin. Thus, VH is a unique cyanogenic glycosidase showing high glycone specificity for the disaccharide vicianoside.