Nishimoto T, Nakada T, Chaen H, Fukuda S, Sugimoto T, Kurimoto M, Tsujisaka Y
a Hayashibara Biochemical Laboratories, Inc. , 7-7 Amase-minamimachi, Okayama 700 , Japan.
b Hayashibara Institute Crop. , 1-2-3 Shimoishii, Okayama 700 , Japan.
Biosci Biotechnol Biochem. 1996 Jan;60(5):835-9. doi: 10.1271/bbb.60.835.
Thermostable trehalose synthase, which catalyzes the conversion of maltose into trehalose by intramolecular transglucosylation, was purified from a cell-free extract of the thermophilic bacterium Thermus aquaticus ATCC 33923 to an electrophoretically homogeneity by successive column chromatographies. The purified enzyme had a molecular weight of 105,000 by SDS-polyacrylamide gel electrophoresis and a pI of 4.6 by gel isoelectrofocusing. The N-terminal amino acid of the enzyme was methionine. The optimum pH and temperature were pH 6.5 and 65°C, respectively. The enzyme was stable from pH 5.5 to 9.5 and up to 80°C for 60min. The trehalose synthase from Thermus aquaticus is more thermoactive and thermostable than that from Pimelobacter sp. R48. The yield of trehalose from maltose by the enzyme was independent of the substrate concentration, and tended to increase at lower temperatures. The maximum yield of trehalose from maltose by the enzyme reached 80-82% at 30-40°C. The activity was inhibited by Cu(2+) , Hg(2+), Zn(2+), and Tris.
通过连续柱色谱法从嗜热栖热菌Thermus aquaticus ATCC 33923的无细胞提取物中纯化出热稳定的海藻糖合酶，该酶通过分子内转葡糖基化作用催化麦芽糖转化为海藻糖，达到电泳纯。经SDS-聚丙烯酰胺凝胶电泳测定，纯化后的酶分子量为105,000，经凝胶等电聚焦测定其pI为4.6。该酶的N端氨基酸为甲硫氨酸。最适pH和温度分别为pH 6.5和65℃。该酶在pH 5.5至9.5范围内稳定，在80℃下可稳定60分钟。嗜热栖热菌的海藻糖合酶比皮杆菌属R48的海藻糖合酶具有更高的热活性和热稳定性。该酶催化麦芽糖生成海藻糖的产率与底物浓度无关，且在较低温度下有增加的趋势。在30 - 40℃时，该酶催化麦芽糖生成海藻糖的最大产率达到80 - 82%。其活性受到Cu(2+)、Hg(2+)、Zn(2+)和Tris的抑制。
