caa a22 4500 397494386 CHVBK 20180308164517.0 cr unu---uuuuu 161202e199502 xx s 000 0 eng 10.1093/jb/117.2.408 doi (NATIONALLICENCE)oxford-10.1093/jb/117.2.408 The Crystal Structures of Mutated 3-Isopropylmalate Dehydrogenase from Thermus thermophilus HB8 and Their Relationship to the Thermostability of the Enzyme [Elektronische Daten] [Hideaki Moriyama, Ko Onodera, Masahiro Sakurai, Nobuo Tanaka, Hiromi Kirino, Tairo Oshima, Yukiteru Katsubet] The structures of two mutant forms (G240A and L246E/V249M) of 3-isopropylmalate dehydrogenase from Thermus thermophilus HB8 were studied by X-ray crystallography. In the case of G240A, the replacement of glycine by alanine at residue 240 was expected to decrease the thermostability as a result of abnormal contacts between the methyl group of alanine and the peptide chain. However, the normal van der Waals' contacts were achieved owing to a shift in a bundle of β-strands that yielded a vacant space for the alanine residue. The extended hydrogen bonds within the β-sheet are the major reason for the decreased thermostability of G240A. The mutations in L246E/V249M are located in an α-helix region which is involved in subunit-subunit contact via hydrophobic interaction. Loosening of the subunit-subunit contact owing to ionic repulsion was the major cause of the lower heat stability of L246E/V249M. © BY THE JOURNAL OF BIOCHEMISTRY Regular Papers nationallicence crystal structures nationallicence 3-isopropylmalate dehydrogenase nationallicence mutation nationallicence thermo stability nationallicence Thermus thermophilus nationallicence Moriyama Hideaki Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut Onodera Ko Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut Sakurai Masahiro Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut Tanaka Nobuo Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut Kirino Hiromi Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut Oshima Tairo Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut Katsubet Yukiteru tinstitute for Protein Research, Osaka University Suita, Osaka 565 aut The Journal of Biochemistry Oxford University Press 117/2(1995-02), 408-413 0021-924X 117:2<408 1995 117 jbchem https://doi.org/10.1093/jb/117.2.408 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jb/117.2.408 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Moriyama Hideaki Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut NATIONALLICENCE 700 1- Onodera Ko Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut NATIONALLICENCE 700 1- Sakurai Masahiro Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut NATIONALLICENCE 700 1- Tanaka Nobuo Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut NATIONALLICENCE 700 1- Kirino Hiromi Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut NATIONALLICENCE 700 1- Oshima Tairo Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology Nagatsuta, Midori-ku, Yokohama 227 aut NATIONALLICENCE 700 1- Katsubet Yukiteru tinstitute for Protein Research, Osaka University Suita, Osaka 565 aut NATIONALLICENCE 773 0- The Journal of Biochemistry Oxford University Press 117/2(1995-02), 408-413 0021-924X 117:2<408 1995 117 jbchem Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford