RESUMO
This review discusses the catalytic properties, activity regulation, structure, and functions of O-glycoside hydrolases from marine organisms exemplified by endo-1â3-ß-D-glucanases of marine invertebrates.
Assuntos
Organismos Aquáticos/enzimologia , Glucana Endo-1,3-beta-D-Glucosidase/metabolismo , Animais , Glucana Endo-1,3-beta-D-Glucosidase/química , Glucanos/química , Glucanos/metabolismo , Moluscos/enzimologia , Polissacarídeos/química , Polissacarídeos/metabolismo , Estrutura Terciária de Proteína , Especificidade por SubstratoRESUMO
An aryl sulfatase of unusual specificity has been isolated from the liver of marine mollusk Littorina kurila. It hydrolyzes p-nitrophenyl sulfate, does not affect the natural fucoidan, and catalyzes splitting off of the sulfate group in position C4 of xylose residues within the carbohydrate chains of holostane triterpene glycosides from sea cucumbers. The properties of the enzyme were studied at pH 5.4. The protein is homogeneous according to electrophoresis and has M 45 +/- 1 kDa. The semiinactivation time of the enzyme at 60 degrees C is 20 min, and its Km value for the hydrolysis of p-nitrophenyl sulfate is 8.7 +/- 1 mM. It was shown that natural sulfated polyhydroxysteroids inhibit activity of the sulfatase; their I50 values depend on their structures and are within the range from 10(-3) to 10(-5) M.