title: Substrate specificity of beta-primeverosidase, a key enzyme in aroma formation during oolong tea and black tea manufacturing.
abstract: We synthesized nine kinds of diglycosides and a monoglycoside of 2-phenylethanol to investigate the substrate specificity of the purified beta-primeverosidase from fresh leaves of a tea cultivar (Camellia sinensis var. sinensis cv. Yabukita) in comparison with the apparent substrate specificity of the crude enzyme extract from tea leaves. The crude enzyme extract mainly showed beta-primeverosidase activity, although monoglycosidases activity was present to some extent. The purified beta-primeverosidase showed very narrow substrate specificity with respect to the glycon moiety, and especially prominent specificity for the beta-primeverosyl (6-O-beta-D-xylopyranosyl-beta-D-glucopyranosyl) moiety. The enzymes hydrolyzed naturally occurring diglycosides such as beta-primeveroside, beta-vicianoside, beta-acuminoside, beta-gentiobioside and 6-O-alpha-L-arabinofuranosyl-beta-D-glucopyranoside, but were unable to hydrolyze synthetic unnatural diglycosides. The purified enzyme was inactive toward 2-phenylethyl beta-D-glucopyranoside. The enzyme hydrolyzed each of the diglycosides into the corresponding disaccharide and 2-phenylethanol. These results indicate the beta-primeverosidase, a diglycosidase, to be a key enzyme involved in aroma formation during the tea manufacturing process.
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Japan.
authors.forename: S J
authors.initials: SJ
authors.lastname: Ma
authors.forename: M
authors.initials: M
authors.lastname: Mizutani
authors.forename: J
authors.initials: J
authors.lastname: Hiratake
authors.forename: K
authors.initials: K
authors.lastname: Hayashi
authors.forename: K
authors.initials: K
authors.lastname: Yagi
authors.forename: N
authors.initials: N
authors.lastname: Watanabe
authors.forename: K
authors.initials: K
authors.lastname: Sakata
mesh_terms: D002240:Carbohydrate Sequence; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D006026:Glycoside Hydrolases / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009812:Odorants; D010940:Plant Proteins; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013379:Substrate Specificity; D013662:Tea / Q000737:chemistry*
chemical_list: D010940:Plant Proteins; D013662:Tea; D006026:Glycoside Hydrolases; C460087:beta-primeverosidase