Kolstad G, Synstad B, Eijsink V G H, van Aalten D M F
Department of Chemistry and Biotechnology, Agricultural University of Norway, 1432 As, Norway.
Acta Crystallogr D Biol Crystallogr. 2002 Feb;58(Pt 2):377-9. doi: 10.1107/s0907444901018972. Epub 2002 Jan 24.
The crystal structure of the inactive D140N mutant of Serratia marcescens was refined to 1.45 A resolution. The structure of the mutant was essentially identical to that of the wild type, with the exception of a rotation of Asp142 in the catalytic centre. In the mutant, this residue interacts with the catalytic acid (Glu144) and not with residue 140 as in the wild type. Thus, the 500-fold decrease in activity in the D140N mutant seems to be largely mediated by an effect on Asp142, confirming the crucial role of the latter residue in catalysis.
粘质沙雷氏菌无活性D140N突变体的晶体结构被精修至1.45埃分辨率。该突变体的结构与野生型基本相同，只是催化中心的天冬氨酸142发生了旋转。在突变体中，该残基与催化酸（谷氨酸144）相互作用，而不像野生型那样与残基140相互作用。因此，D140N突变体中活性降低500倍似乎很大程度上是由对天冬氨酸142的影响介导的，这证实了后一个残基在催化中的关键作用。
