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The effects of multiple ancestral residues on the Thermus thermophilus 3‐isopropylmalate dehydrogenase
Author(s) -
Watanabe Keiko,
Yamagishi Akihiko
Publication year - 2006
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2006.06.012
Subject(s) - thermus thermophilus , mutant , wild type , thermus , dehydrogenase , biology , enzyme , point mutation , genetics , residue (chemistry) , biochemistry , chemistry , thermophile , gene , escherichia coli
Previously, we showed that mutants of Thermus thermophilus 3‐isopropylmalate dehydrogenase (IPMDH) each containing a residue (ancestral residue) that had been predicted to exist in a postulated common ancestor protein often have greater thermal stabilities than does the contemporary wild‐type enzyme. In this study, the combined effects of multiple ancestral residues were analyzed. Two mutants, containing multiple mutations, Sup3mut (Val181Thr/Pro324Thr/Ala335Glu) and Sup4mut (Leu134Asn/Val181Thr/Pro324Thr/Ala335Glu) were constructed and show greater thermal stabilities than the wild‐type and single‐point mutant IPMDHs do. Most of the mutants have similar or improved catalytic efficiencies at 70 °C when compared with the wild‐type IPMDH.