title: Heat stability of the potato tuber ADP-glucose pyrophosphorylase: role of Cys residue 12 in the small subunit.
abstract: Most of the ADP-glucose pyrophosphorylases from different sources are stable to a heat treatment. We found that in the potato (Solanum tuberosum L.) tuber enzyme, the intermolecular disulfide bridge located between Cys12 of the small subunits is responsible for the stability at 60 degrees C. When this unique disulfide bond is cleaved the enzyme is stable up to 40 degrees C. Mutation of Cys12 in the small subunit into either Ala or Ser yielded enzymes with stability similar to the reduced form of the wild type. Concurrently, the enzyme with a truncated small subunit on the N-terminal was stable only up to 40 degrees C. Thus, the N-terminal is important for the stability of the enzyme because of the presence of a disulfide bond.
authors: Department of Biochemistry, Michigan State University, East Lansing, Michigan, 48824, USA.
authors: M A
authors: MA
authors: Ballicora
authors: Y
authors: Y
authors: Fu
authors: J B
authors: JB
authors: Frueauf
authors: J
authors: J
authors: Preiss
mesh_terms: D000245:Adenosine Diphosphate Glucose / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D003545:Cysteine / Q000235:genetics / Q000378:metabolism*; D004220:Disulfides / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D004795:Enzyme Stability / Q000187:drug effects; D051599:Glucose-1-Phosphate Adenylyltransferase; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D018517:Plant Roots / Q000201:enzymology; D011485:Protein Binding; D011487:Protein Conformation; D016415:Sequence Alignment; D017384:Sequence Deletion; D011198:Solanum tuberosum / Q000201:enzymology*
chemical_list: D004220:Disulfides; D000245:Adenosine Diphosphate Glucose; D009713:Nucleotidyltransferases; D051599:Glucose-1-Phosphate Adenylyltransferase; D003545:Cysteine; D004229:Dithiothreitol