COMPARATIVE STRUCTURAL, BIOCHEMICAL AND KINETIC STUDIES BETWEEN THERMOSTABLE AND COLD-ADAPTED GLUCOAMYLASES

WAYLLACE, N. M.; BUSI, M.V.; GOMEZ CASATI, D.F.

MENDOZA

Congreso; LVIII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2022

SAIB - Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Glucoamylases (GAs, EC 3.2.1.3, glucan 1,4-α-glucosidase) are hydrolytic enzymes also known as amyloglucosidases. GAs belong to the GH15 and GH97 families of glycoside hydrolases (www.cazy.org). These enzymes are exo-amylases that hydrolyze α-1,4 glycosidic bonds by the successive removal of glucose residues from the non-reducing end of starch and related substrates, releasing β-D-glucose. In previous studies, we identified and characterized two novel GAs: Te GA, from Thermoanaerobacter ethanolicus , a thermophilic anaerobic bacterium and Sd GA, from Saccharophagus degradans , a marine bacterium which degrades different complex polysaccharides at high rate. TeGA is a thermophilic enzyme while SdGA is a cold-adapted enzyme. Structurally, these proteins are composed by an Nterminal GH15_N domain linked to a C-terminal catalytic domain (CD), found in the GH15 family ofglycosyl hydrolases. In this study we compared the global structure, catalytic residues, catalytic clefts and the flexibility of SdGA, TeGA and other thermophilic, cold-adapted and psicrophilic enzymes. We identified some characteristics of cold-adapted GAs that would explain the adaptation of these enzymes to low temperature.