The Biosynthesis of d-Apiose in Lemna minor

• Published in: The Journal of biological chemistry Vol. 242; no. 7; pp. 1629 - 1634
• Main Authors: Picken, J M, Mendicino, J
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 10.04.1967
• Subjects: Acetates - metabolism; Carbon Isotopes; Cell Wall - metabolism; Glucose - metabolism; In Vitro Techniques; Methionine - metabolism; Periodic Acid; Plants - metabolism; Polysaccharides - biosynthesis; Serine - metabolism; Space life sciences; Tetroses - biosynthesis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)96138-7

Lemna minor incorporates radioactivity from d -glucose-1- 14 C, d -glucose-2- 14 C, d -glucose-3,4- 14 C, d -glucose-6- 14 C, sodium acetate-2- 14 C, dl -serine-3- 14 C, and l -methionine- 14 CH 3 into the d -apiose moiety of cell wall polysaccharide. The mechanism of biosynthesis of this hydroxymethyltetrose was studied by determining the distribution of 14 C in d -apiose after feeding various labeled precursors. Labeled d -apiose was isolated from this tissue, and an aliquot was reduced to d -apiitol. These two compounds were then oxidized with periodate to formic acid, formaldehyde, and glycolic acid, and the radioactivity in each of the carbon atoms of d -apiose was determined. The results show that d -glucose can serve as a precursor for all of the carbon atoms of d -apiose in L. minor , whereas acetate and dl -serine are probably converted to d -glucose before being incorporated into d -apiose. The evidence obtained in this study indicates that d -apiose is derived from d -glucose by the loss of carbon atom 6, followed by a branching reaction which occurs without randomization, and converts either C-3 or C-4 of d -glucose to one of the hydroxymethyl groups of d -apiose.