Characterization of a lactate oxidase from a strain of gram negative bacterium from soil.
A lactate oxidase was purified about 36-fold from a newly screened strain KY6 of gram negative bacterium from soil to yield a homogeneous protein. The native enzyme had a molecular mass of 204 kDa measured by Sephadex G-200 and that of subunit on the SDS-PAGE was found to be 45 kDa. The enzyme was optimally active at pH 7.7 and showed stability at pH range of 5.7 to 9.5 for 24 h at 4 degrees C. The optimum temperature was 70 degrees C and the enzyme activity was stable for 10 min up to 45 degrees C. The half-life of the enzyme activity was about 10 min at 55 degrees C. The best substrate of the enzyme was D-lactate and Km value for D-lactate was 0.14 mM. The Km value for DL-lactate was 0.20 mM. Substrate inhibition of the enzyme was observed at higher concentrations than 20 mM of DL-lactate and 10 mM of D-lactate.
Xu
P
P
Department of Food Science and Technology, Kyoto University, Japan.
Yano
T
T
Yamamoto
K
K
Suzuki
H
H
Kumagai
H
H
D006090:Gram-Negative Bacteria / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000302:isolation & purification* / Q000378:metabolism; D012988:Soil Microbiology
D006899:Mixed Function Oxygenases; C021497:lactate 2-monooxygenase