Last Step in the Conversion of Trehalose to Glycogen

• DOI: 10.1074/jbc.m109.033944
• Publication Date: 2010-01-30T04:00:20Z
• Authors: Alan D. Elbein; Irena Pastuszak; Alan J. Tackett; Tyler Wilson; Yuan T. Pan
• Keywords: Maltotriose; Glycogen branching enzyme

We show that Mycobacterium smegmatis has an enzyme catalyzing transfer of maltose from [(14)C]maltose 1-phosphate to glycogen. This was purified 90-fold crude extracts and characterized. Maltose required addition acceptor. Liver, oyster, or mycobacterial glycogens were the best acceptors, whereas amylopectin had good activity, but amylose a poor Maltosaccharides inhibited [(14)C]maltose-1-P glycogen because they also acceptors maltose, caused production larger sized radioactive maltosaccharides. When maltotetraose acceptor, over 90% (14)C-labeled product maltohexaose, no radioactivity in maltopentaose, demonstrating transferred intact. Stoichiometry showed 0.89 micromol inorganic phosphate produced for each micromole glycogen, 56% added maltose-1-P been named alpha1,4-glucan:maltose-1-P maltosyltransferase (GMPMT). Transfer by micromolar amounts arsenate only slightly millimolar concentrations glucose-1-P, glucose-6-P, pyrophosphate. GMPMT compared with phosphorylase (GP). catalyzed [(14)C]maltose-1-P, not [(14)C]glucose-1-P, GP glucose-1-P maltose-1-P. both 1,4-dideoxy-1,4-imino-d-arabinitol, isofagomine. Because mycobacteria contain trehalose synthase accumulate large when grown high trehalose, we propose synthase, maltokinase, represent new pathway synthesis using as source glucose.