title: Production of 2-phenylethanol in roses as the dominant floral scent compound from L-phenylalanine by two key enzymes, a PLP-dependent decarboxylase and a phenylacetaldehyde reductase.
abstract: We investigated the biosynthetic pathway for 2-phenylethanol, the dominant floral scent compound in roses, using enzyme assays. L-[(2)H8] Phenylalanine was converted to [(2)H8] phenylacetaldehyde and [(2)H8]-2-phenylethanol by two enzymes derived from the flower petals of R. 'Hoh-Jun,' these being identified as pyridoxal-5'-phosphate-dependent L-aromatic amino acid decarboxylase (AADC) and phenylacetaldehyde reductase (PAR). The activity of rose petal AADC to yield phenylacetaldehyde was nine times higher toward L-phenylalanine than toward its D-isomer, and this conversion was not inhibited by iproniazid, a specific inhibitor of monoamine oxidase. Under aerobic conditions, rose petal AADC stoichiometrically produced NH3 together with phenylacetaldehyde during the course of decarboxylation and oxidation, followed by the hydrolysis of L-phenylalanine. Phenylacetaldehyde was subsequently converted to 2-phenylethanol by the action of PAR. PAR showed specificity toward several volatile aldehydes.
authors.affiliation: The United Graduate School of Agricultural Science, Gifu University (Shizuoka University), Japan.
authors.forename: Miwa
authors.initials: M
authors.lastname: Sakai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hirata
authors.forename: Hironori
authors.initials: H
authors.lastname: Sayama
authors.forename: Kazuya
authors.initials: K
authors.lastname: Sekiguchi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Itano
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Asai
authors.forename: Hideo
authors.initials: H
authors.lastname: Dohra
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hara
authors.forename: Naoharu
authors.initials: N
authors.lastname: Watanabe
mesh_terms: D000079:Acetaldehyde / Q000031:analogs & derivatives / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008956:Models, Chemical; D015394:Molecular Structure; D010649:Phenylalanine / Q000737:chemistry / Q000378:metabolism*; D010626:Phenylethyl Alcohol / Q000737:chemistry / Q000378:metabolism*; D027826:Rosa / Q000201:enzymology / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D010649:Phenylalanine; D000429:Alcohol Oxidoreductases; C110191:phenylacetaldehyde reductase; D001142:Aromatic-L-Amino-Acid Decarboxylases; D000079:Acetaldehyde; D010626:Phenylethyl Alcohol; C013192:phenylacetaldehyde