title: A novel multifunctional α-amylase from the thermophilic fungus Malbranchea cinnamomea: biochemical characterization and three-dimensional structure.
abstract: A novel α-amylase (McAmyA) from the thermophilic fungus, Malbranchea cinnamomea was purified, characterized and crystallized in the present study. McAmyA was purified to apparent homogeneity with a molecular mass of 60.3 kDa on SDS-PAGE. The enzyme exhibited maximal activity at pH 6.5 and was stable within pH 5.0-10.0. It was most active at 65 °C and was stable up to 50 °C. McAmyA was capable of hydrolyzing amylose, starch, amylopectin, pullulan, cyclodextrins and maltooligosaccharides. The full-length cDNA of an α-amylase gene (McAmyA) from the strain was cloned. McAmyA consisted of a 1,476-bp open reading frame encoding 492 amino acids. It displayed the highest amino acid sequence homology (less than 60 %) with the reported α-amylases. The crystal structure of McAmyA was solved at a resolution of 2.25 Å (PDB code 3VM7). The overall structure of McAmyA reveals three domains with ten α helices and 14 β strands, and the putative catalytic residues are positioned at domain A with somewhat different secondary structural circumstances compared with typical α-amylases.
authors.affiliation: Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, PO Box 294, No.17 Qinghua Donglu, Haidian District, Beijing, 100083, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Han
authors.forename: Peng
authors.initials: P
authors.lastname: Zhou
authors.forename: Songqing
authors.initials: S
authors.lastname: Hu
authors.forename: Shaoqing
authors.initials: S
authors.lastname: Yang
authors.forename: Qiaojuan
authors.initials: Q
authors.lastname: Yan
authors.forename: Zhengqiang
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D000687:Amylopectin / Q000737:chemistry; D000688:Amylose / Q000737:chemistry; D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D004789:Enzyme Activation; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D018076:DNA, Complementary; D004271:DNA, Fungal; D005656:Fungal Proteins; D000688:Amylose; D000687:Amylopectin; D000516:alpha-Amylases