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Disproportionating enzyme (4-a-Glucanotransferase; EC 2.4.1.25) of potato
journal contribution
posted on 2023-05-18, 11:29 authored by Takaha, T, Yanase, M, Okada, S, Steven SmithSteven SmithDisproportionating enzyme (D-enzyme, 4-a-glucanotransferase; EC 2.4.1.25) has been purified to homogeneity from potato tubers and its activity characterized. The enzyme catalyzes the transfer of maltooligosaccharides from one 1,4-a-~-glucan molecule to another, or to glucose. Maltooligosaccharides are effective donor molecules, but short chain amylose and amylopectin may also function as donors. Enzyme activity is not affected by inorganic phosphate, S-phosphoglycerate, or hexose phosphates. A cDNA clone encoding the enzyme was isolated using oligonucleotide probes derived from partial peptide sequences of the purified enzyme. The identity of the cDNA clone was confirmed by expression in Escherichia coli resulting in D-enzyme activity. The amino acid sequence deduced from the cDNA showing significant homology with a 4-a-glucanotransferase from Streptococcus. The deduced sequence indicates the presence of an aminoterminal plastid transit peptide pf 52 amino acid residues and a mature polypeptide of 524 residues. D-enzyme mRNA is present in leaves, stems, roots, and stolons but is most abundant in developing and mature tubers. The amount of mRNA in leaves increases in response to light and to- sucrose added to the medium. These results are discussed in terms of the function of D-enzyme in potato starch metabolism.
History
Publication title
Journal of Biological ChemistryVolume
268Pagination
1391-1396ISSN
0021-9258Department/School
School of Natural SciencesPublisher
Amer Soc Biochemistry Molecular Biology IncPlace of publication
9650 Rockville Pike, Bethesda, USA, Md, 20814-3996Rights statement
Copyright 1993 The American Society for Biochemistry and Molecular Biology, IncRepository Status
- Restricted