A hexokinase with broad sugar specificity from a thermophilic bacterium
- 作者：Jungdon Bae ; Dooil Kim ; Yongseok Choi ; Sukhoon Koh ; Jung Eun Park ; Joong Su Kim ; Seong Hoon Moon ; Bo-Hyun Park ; Miri Park ; Hye-Eun Song et al.
- 关键词：Thermus ; Glycolysis ; Hexokinase ; ROK ; Substrate specificity ; Molecular modeling
- 刊名：Biochemical and Biophysical Research Communications
- 出版年：2005
- 期刊代码：159_0006291x
- 类别：bio
- 出版时间：2005
- 卷：334
- 期：3
- 页码：754-763
- 文件大小：1348 K
摘要
A recombinant thermophilic Thermus caldophilus GK24 hexokinase, one of the ROK-type (repressor protein, open reading frames, and sugar kinase) proteins, exists uniquely as a 120 kDa molecule with four subunits (31 kDa), in contrast to eukaryotic and bacterial sugar kinases which are monomers or dimers. The optimal temperature and pH for the enzyme reaction are 70–80 °C and 7.5, respectively. This enzyme shows broad specificity toward glucose, mannose, glucosamine, allose, 2-deoxyglucose, and fructose. To understand the sugar specificity at a structural level, the enzyme–ATP/Mg2+–sugar binding complex models have been constructed. It has been shown that the sugar specificity is probably dependent on the interaction energy occurred by the positional proximity of sugars bound in the active site of the enzyme, which exhibits a tolerance to modification at C2 or C3 of glucose.