Revised kinetic parameters of the Aps reductase enzyme: effect on microbial sulfur isotope fractionation.

Shawn E McGlynn; Tommy Po-Hsiang Wang; Mayuko Nakagawa; Yuichiro Ueno

Presentation information

[E] Oral

B (Biogeosciences ) » B-BC Biogeochemistry

[B-BC03] Earth and Planetary Science Frontiers for Life and Global Environment

convener:Yoshinori Takano(Japan Agency for Marine-Earth Science and Technology (JAMSTEC)), Yohey Suzuki(Graduate School of Science, The University of Tokyo), Shingo Kato(RIKEN), Keisuke Fukushi(Institute of Nature & Environmental Technology, Kanazawa University)

[BBC03-11] Revised kinetic parameters of the Aps reductase enzyme: effect on microbial sulfur isotope fractionation.

*Shawn E McGlynn¹, Tommy Po-Hsiang Wang¹, Mayuko Nakagawa¹, Yuichiro Ueno¹ (1.Tokyo Institute of Technology)

Keywords:sulfur isotopes, enzyme kinetics, microbial growth

The Aps reductase enzyme conducts the first redox reaction of microbial sulfate reduction, and it is the most exergonic under a wide array of conditions. We report a new kinetic characterization of the enzyme under non-inhibited conditions using an assay which specifically removes the inhibitor AMP from the assay solution. The Km, and Vmax properties of the enzyme are dramatically altered, which in turn affects predicted whole cell sulfur isotope fractionation. Whether or not the altered kinetics affect the apparent KIE of the enzyme is under investigation.