Article
 

Kinetic Mechanism of the Hydrogen-Oxidizing Hydrogenase from Soybean Nodule Bacteroids

Public Deposited

Downloadable Content

Download PDF
Request Accessible Version
https://ir.library.oregonstate.edu/concern/articles/4t64gn94k

Descriptions

Attribute NameValues
Creator
Abstract
  • The kinetic mechanism of the unidirectional H2-oxidizing hydrogenase from soybean nodule bacteroids has been investigated with highly purified enzyme. Measurements of the K, for H2 vary from 0.97 to 2.6 pM, and the K,,, for methylene blue varies from 6 to 17 pM. With H2 and methylene blue as substrates, the initial velocity patterns are intersecting. High levels of methylene blue are inhibitory (KI = 2.4 mM): the inhibition is competitive vs. H2. CO is a competitive inhibitor of H2 (KI= 157 pM) and noncompetitive vs. methylene blue. O2 inactivates the enzyme (tl12 - 1 h) but also is a reversible inhibitor of hydrogenase activity upon short exposure to low concentrations. Inhibition by O2 is uncom-petitive vs. H2 and noncompetitive vs. methylene blue. Hydrogenase was not inhibited by C2H2; preincubation under C2H2 inactivates the enzyme. Reduced methyl and benzyl viologens support low rates of H2 evolution by the hydrogenase. The K, for reduced methyl viologen is 11 pM. H2 is a potent inhibitor of H2 evolution: the inhibition is noncompetitive vs. reduced methyl viologen. The hydrogenase will catalyze a low rate of exchange in the reaction between D2 and H20 to form both HD and H2. We p r o p a two-site ping-pong mechanism for the enzyme in which H2 is reversibly activated at one site and e- carriers interact at the second site.
  • Keywords: Hydrogen-oxidizing hydrogenase, Soybean nodule bacteroids
Resource Type
DOI
Date Available
Date Issued
Citation
  • Arp, D. J., & Burris, R. H. (1981). Kinetic mechanism of the hydrogen-oxidizing hydrogenase from soybean nodule bacteroids. Biochemistry, 20(8), 2234-2240. doi:10.1021/bi00511a025
Journal Title
Journal Volume
  • 20
Academic Affiliation
Rights Statement
Funding Statement (additional comments about funding)
  • This work was supported by the College of Agricultural and Life Sciences, University of Wisconsin-Madison, by National Science Foundation Grant PCM77- 21038, and by US. Public Health Service Grant AI-00848 from the National Institute of Allergy and Infectious Diseases.
Publisher
Peer Reviewed
Language
Replaces
Accessibility Feature

Relationships

Parents:

This work has no parents.

Items

Thumbnail Title Date Uploaded Visibility Actions
file details ArpDanielJ.Botany.Kineticmechanismof.pdf 2017-07-10 Public Download