Structure and stability of glucoamylase II from Aspergillus niger: A circular dichroism study.
J Biosci
;
1984 Dec; 6(5): 601-611
Artigo
em Inglês
| IMSEAR
| ID: sea-160369
ABSTRACT
Glucoamylase II (EC 3.2.1.3) from Aspergillus niger has 31 % α-helix, 36 % ßstructure and rest aperiodic structure at pH 4·8 as analysed by the method of Provencher and Glockner (1981, Biochemistry, 20,33). In the near ultra-violet circular dichroism spectrum the enzyme exhibits peaks at 304, 289, 282 and 257 nm and troughs at 285, 277 and 265 nm respectively. The enzyme activity and structure showed greater stability at pH 4·8 than at pH 7·0, were highly sensitive to alkaline pH but less sensitive to acid pH values. The enzyme retained most of its catalytic activity and structure even on partial removal of carbohydrate moieties by periodate treatment but was less stable at higher temperatures and storage at 30°C. Reduction of the periodate treated enzyme did not reverse the loss of stability. Binding of the synthetic substrate,p-nitrophenyl-α-D-glucoside, perturbed the environment around aromatic amino acids and caused a decrease in the ordered structure.
Texto completo:
DisponíveL
Índice:
IMSEAR (Sudeste Asiático)
Idioma:
Inglês
Revista:
J Biosci
Ano de publicação:
1984
Tipo de documento:
Artigo
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