变形链球菌a型血清型细胞外葡糖基转移酶的纯化及特性，该酶可合成1,6-、1,3-α-D-葡聚糖

Purification and properties of extracellular glucosyltransferase synthesizing 1,6-, 1,3-alpha-D-glucan from Streptococcus mutans serotype a.

作者信息

Tsumori H, Shimamura A, Mukasa H

出版信息

J Gen Microbiol. 1985 Dec;131(12):3347-53. doi: 10.1099/00221287-131-12-3347.

Abstract

An extracellular glucosyltransferase (sucrose: 1,6-, 1,3-alpha-D-glucan 3-alpha- and 6-alpha-D-glucosyltransferase, EC 2.4.1.-) of Streptococcus mutans HS6 (serotype a) was purified from culture supernatant by DEAE-Sepharose chromatography and preparative isoelectric focusing. The molecular weight measured by SDS-PAGE was 159 000 and the isoelectric point was pH 4.9. The specific activity was 89.7 i.u. (mg protein)-1 and the optimum pH was 6.0. The Km value for sucrose was 4.9 mM and the enzyme activity was not stimulated by exogenous dextran T10. Glucan was synthesized de novo from sucrose by the purified enzyme and consisted of 49.1 mol% 1,6-alpha-linked glucose and 33.9 mol% 1,3-alpha-linked glucose, with 13.6 mol% terminal glucose and 3.3 mol% 1,3,6-alpha-branched glucose.

摘要

变形链球菌HS6（血清型a）的一种胞外葡糖基转移酶（蔗糖：1,6 -、1,3 -α-D-葡聚糖3-α-和6-α-D-葡糖基转移酶，EC 2.4.1.-）通过DEAE-琼脂糖凝胶色谱和制备性等电聚焦从培养上清液中纯化得到。通过SDS-PAGE测定的分子量为159 000，等电点为pH 4.9。比活性为89.7 i.u.（mg蛋白）-1，最适pH为6.0。蔗糖的Km值为4.9 mM，外源葡聚糖T10不刺激该酶的活性。纯化的酶可从蔗糖从头合成葡聚糖，其由49.1 mol%的1,6-α-连接葡萄糖、33.9 mol%的1,3-α-连接葡萄糖、13.6 mol%的末端葡萄糖和3.3 mol%的1,3,.-α-分支葡萄糖组成。