| Title | Kinetic and spectral investigations on Ca^2+ and Sr^2+ containing methanol dehydrogenases |
|---|---|
| Author | Kim, Si Wouk * · Kim, Chung, Sung¹ · Lee, Jung Sup¹ · Koh, Moon Joo² · Yang, Song Suk · Duine, Johannis A.³ · Kim, Young Min⁴ |
| Address | Department of Environmental Engineering; ¹Department of Genetic Engineering; ²Department of Chemistry, Chosun University; ³Department of Microbiology and Enzymology, Delft University of Technology; ⁴Department of Biology, Yonsei University |
| Bibliography | Journal of Microbiology, 35(3),200-205, 1997, |
| DOI | |
| Key Words | Methanol dehydrogenase, pyrroloquinoline quinone, Methylobacillus methanolovorus sp. strain SK5 |
| Abstract | Both Ca^2+ and Sr^2+ containing methanol dehydrogenases (MDH) were purified to homogeneity with yields of 48% and 42%, respectively, from Methylabacillus methanolovorus sp. strain SK5. Most of the biochemical and structural properties were similar to each other. However, some differences were found: (1) although the overall shape of the absorption spectrum of Sr^2+ MDH was very similar to that of Ca^2+ MDH, the absorption intensity originating from the cofactor in Sr^2+. MDH was higher than that in Ca^2+-MDH. Small blue shift of the maximum was also observed. These are probably due to a difference in redox state of the cofactors in Ca^2+ and Sr^2+ -MDH; (2)Sr^2+ -MDH was more heat-stable than Ca^2+-MDH above 56℃; (3) the V_max values for the methanol-dependent activities of Sr^2+ Ca^2+ -MDH in the presence of 3 mM KCN were 2.038 and 808 nmol/mg protein/min, respectively. In addition, the K_m values of Sr^2+ and Ca^2+ MDH for methanol were 12 and 21 uM, respectively; (4) the endogenous activity of Ca^2+ -MDH was more sensitive than that of Sr^2+ -MDH in the presence of cyanide; (5) Diethyl pyrocarbonate treatment increased the enzyme activities of Ca^2+ and Sr^2+ MDH 4.2 and 1.4 folds, respectively. These results indicate that Sr^2+ stabilizes the structural conformation and enhances the activity of MDH more than Ca^2+. |
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