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Stability‐increasing mutants of glucose dehydrogenase
Author(s) -
Nagao Toshihiro,
Makino Yasutaka,
Yamamoto Keizo,
Urabe Itaru,
Okada Hirosuke
Publication year - 1989
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 - 10.1016/0014-5793(89)80941-x
Subject(s) - thermostability , mutant , enzyme , biochemistry , chemistry , wild type , dehydrogenase , gene
Four stability‐increasing mutants of glucose dehydrogenase from Bacillus megateriun were purified together with the wild‐type enzyme; each has a single amino acid change of Glu‐96 to Gly, Glu‐96 to Ala, Gln‐252 to Leu, or Tyr‐253 to Cys. These mutant enzymes are more heat resistant at pH 6.5 than the wild‐type enzyme; the replacement of Glu‐96 by Ala increases the thermostability by about 20°C. The mutant enzymes are also resistant to inactivation in alkaline solutions. The replacement of Glu‐96 by Gly or Ala protects the enzyme from alkaline inactivation almost completely. The kinetic constants for the activities of these mutant enzymes do not differ significantly from those of the wild‐type enzyme.