López-Cortés Nieves, Reyes-Duarte Dolores, Beloqui Ana, Polaina Julio, Ghazi Iraj, Golyshina Olga V, Ballesteros Antonio, Golyshin Peter N, Ferrer Manuel
Institute of Catalysis, CSIC, Cantoblanco, 28049 Madrid, Spain.
FEBS Lett. 2007 Oct 2;581(24):4657-62. doi: 10.1016/j.febslet.2007.08.060. Epub 2007 Sep 4.
An acetylxylan esterase (R.44), belonging to the carbohydrate esterase family 6 (CE6), retrieved from bovine rumen metagenome was analyzed. Molecular modelling and site-directed mutagenesis indicated that the enzyme possesses a catalytic triad formed by Ser(14), His(231) and Glu(152). The catalytic Ser and His have been identified in highly conserved sequences GQSX and DXXH in the CE6 family, respectively, and the active-site glutamate was part of a highly conserved sequence HQGE. This motif is situated near to the so-called Block III in the CE6 family and its role in catalysis has not been identified so far.
对从牛瘤胃宏基因组中获取的一种属于碳水化合物酯酶家族6（CE6）的乙酰木聚糖酯酶（R.44）进行了分析。分子建模和定点诱变表明，该酶具有由Ser(14)、His(231)和Glu(152)形成的催化三联体。催化性丝氨酸和组氨酸分别在CE6家族的高度保守序列GQSX和DXXH中被鉴定出来，活性位点谷氨酸是高度保守序列HQGE的一部分。该基序位于CE6家族中所谓的Block III附近，其在催化中的作用迄今尚未确定。
