Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.\)Ī protein’s primary structure is the unique sequence of amino acids in each polypeptide chain that makes up the protein. Furthermore, an explanation of the α-glucosidase reaction mechanism is proposed based on the glucosyl-enzyme intermediate structure. Two residues, Thr203 and Phe297, assisted with Gly228, were found to determine the glycosidic linkage specificity of the substrate at subsite +1. A peculiar long β → α loop 4 which exists in α-glucosidase is responsible for the strict recognition of disaccharides owing to steric hindrance. These structures explicitly provide insights into the substrate specificity and catalytic mechanism of HaG. In this study, four crystal structures of HaG were solved: the apo form, the glucosyl-enzyme intermediate complex, the E271Q mutant in complex with its natural substrate maltose and a complex of the D202N mutant with D-glucose and glycerol. Although several three-dimensional structures of GH13 members have been solved, the disaccharide specificity and α-(1 → 4) recognition mechanism of α-glucosidase are unclear owing to a lack of corresponding substrate-bound structures. H11 α-glucosidase (HaG), belonging to glycoside hydrolase family 13 (GH13), only has high hydrolytic activity towards the α-(1 → 4)-linked disaccharide maltose among naturally occurring substrates. The primary structure of the proteins is the exact ordering of certain amino acids that form the chains. Introduction C: Loops and irregular elements (corresponding to the blank characters output by DSSP) E: -strand H: -helix B: -bridge G: 3-helix I:. The main involvement of the secondary structures is in the creation of structures that include ligaments and cartilages amongst many others. Structure of Alpha Helix, Beta Plates and Beta. The main involvement of the primary structures is in the post-translational processes. Α-Glucosidases, which catalyze the hydrolysis of the α-glucosidic linkage at the nonreducing end of the substrate, are important for the metabolism of α-glucosides. The Four Levels of Structures of Proteins: Primary, Secondary, Tertiary and Quaternary Structure of Proteins. Diversity, Equity, Inclusion, and Access.Citation, Usage, Privacy Policies, Logo.Biologically Interesting Molecule Reference Dictionary (BIRD).
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