Hirose R, Suzuki T, Moriyama H, Sato T, Yamagishi A, Oshima T, Tanaka N
Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8501, Japan.
Protein Eng. 2001 Feb;14(2):81-4. doi: 10.1093/protein/14.2.81.
Random mutagenesis on thermophilic 3-isopropylmalate dehydrogenases (IPMDH; EC 1.1.1.85) produced mutant enzymes which adapt to low temperatures. These mutants had higher activity at lower temperatures than the wild-type enzyme without losing high thermostability. Here we report three structures of the mutants of Thermus thermophilus IPMDH determined by X-ray diffraction which was adapted to a low-temperature environment. Two of them have unstable coenzyme binding states and the other one probably has a stable substrate binding state. The present research suggests that the adaptation is correlated with the binding of either coenzyme or the substrate.
对嗜热3-异丙基苹果酸脱氢酶（IPMDH；EC 1.1.1.85）进行随机诱变产生了适应低温的突变酶。这些突变体在较低温度下比野生型酶具有更高的活性，且不会丧失高热稳定性。在此，我们报告了通过X射线衍射确定的嗜热栖热菌IPMDH突变体的三种结构，这些突变体适应了低温环境。其中两个具有不稳定的辅酶结合状态，另一个可能具有稳定的底物结合状态。本研究表明，这种适应性与辅酶或底物的结合相关。
