This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (53) Citing Articles via Google Scholar Google Scholar Articles by Negm, F. B. Articles by Loescher, W. H. Search for Related Content PubMed PubMed Citation Articles by Negm, F. B. Articles by Loescher, W. H. Agricola Articles by Negm, F. B. Articles by Loescher, W. H.

Articles

Detection and Characterization of Sorbitol Dehydrogenase from Apple Callus Tissue ^1,2

^a Department of Horticulture and Landscape Architecture, Washington State University, Pullman, Washington 99164

Sorbitol dehydrogenase (L-iditol:NAD⁺ oxidoreductase, EC 1.1.1.14) has been detected and characterized from apple (Malus domestica cv. Granny Smith) mesocarp tissue cultures. The enzyme oxidized sorbitol, xylitol, L-arabitol, ribitol, and L-threitol in the presence of NAD. NADP could not replace NAD. Mannitol was slightly oxidized (8% of sorbitol). Other polyols that did not serve as substrate were galactitol, myo-inositol, D-arabitol, erythritol, and glycerol. The dehydrogenase oxidized NADH in the presence of D-fructose or L-sorbose. No detectable activity was observed with D-tagatose. NADPH could partially substitute for NADH.

Maximum rate of NAD reduction in the presence of sorbitol occurred in tris(hydroxymethyl)aminomethane-HCl buffer (pH 9), or in 2-amino-2-methyl-1,3-propanediol buffer (pH 9.5). Maximum rates of NADH oxidation in the presence of fructose were observed between pH 5.7 and 7.0 with phosphate buffer. Reaction rates increased with increasing temperature up to 60 C. The K_m for sorbitol and xylitol oxidation were 86 millimolar and 37 millimolar, respectively. The K_m for fructose reduction was 1.5 molar.

Sorbitol oxidation was completely inhibited by heavy metal ions, iodoacetate, p-chloromercuribenzoate, and cysteine. ZnSO₄ (0.25 millimolar) reversed the cysteine inhibition. It is suggested that apple sorbitol dehydrogenase contains sulfhydryl groups and requires a metal ion for full activity.

² A preliminary report of this work was presented at the ASPP meeting in June 1978.

This article has been cited by other articles:

				X.-L. Wang, Y.-H. Xu, C.-C. Peng, R.-C. Fan, and X.-Q. Gao Ubiquitous distribution and different subcellular localization of sorbitol dehydrogenase in fruit and leaf of apple J. Exp. Bot., March 1, 2009; 60(3): 1025 - 1034. [Abstract] [Full Text] [PDF]

				R. Zhou, L. Cheng, and A. M. Dandekar Down-regulation of sorbitol dehydrogenase and up-regulation of sucrose synthase in shoot tips of the transgenic apple trees with decreased sorbitol synthesis J. Exp. Bot., November 1, 2006; 57(14): 3647 - 3657. [Abstract] [Full Text] [PDF]