Characterization of recombinant glyoxylate reductase from thermophile Thermus thermophilus HB27.
A glyoxylate reductase gene from the thermophilic bacterium Thermus thermophilus HB27 (TthGR) was cloned and expressed in Escherichia coli cells. The recombinant enzyme was highly purified to homogeneity and characterized. The purified TthGR showed thermostability up to 70 degrees C. In contrast, the maximum reaction condition was relatively mild (45 degrees C and pH 6.7). Although the kcat values against co-enzyme NADH and NADPH were similar, the Km value against co-enzyme NADH was approximately 18 times higher than that against NADPH. TthGR prefers NADPH rather than NADH as an electron donor. These results indicate that a phosphate group of a co-enzyme affects the binding affinity rather than the reaction efficiency, and TthGR demands appropriate amount of phosphate for a high activity. Furthermore, it was found that the half-lives of TthGR in the presence of 25% dimethyl sulfoxide and diethylene glycol were significantly longer than that in the absence of an organic solvent.
Ogino
Hiroyasu
H
Department of Chemical Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan. ogino@chemeng.osakafu-u.ac.jp
Nakayama
Hitoshi
H
China
Hideyasu
H
Kawata
Takuya
T
Doukyu
Noriyuki
N
Yasuda
Masahiro
M
D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics*; D002942:Circular Dichroism; D003001:Cloning, Molecular; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011994:Recombinant Proteins; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet; D016963:Thermus thermophilus / Q000201:enzymology / Q000235:genetics*
D011994:Recombinant Proteins; D012997:Solvents; D000429:Alcohol Oxidoreductases; C020830:glyoxylate reductase