Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1927457 | Archives of Biochemistry and Biophysics | 2006 | 8 Pages |
Abstract
Phosphomevalonate kinase catalyzes the phosphorylation of phosphomevalonate to diphosphomevalonate by ATP, one of the initial steps in the biosynthesis of steroids and isoprenoids. In previous studies, the enzyme from pig liver was purified and characterized, and preliminary work showed that the enzyme follows hyperbolic kinetics and a sequential mechanism. The present work is a more detailed analysis of its kinetic mechanism, using initial velocity and isotope exchange at equilibrium measurements. The results are compatible with a Bi Bi sequential ordered mechanism with phosphomevalonate as the first substrate and ADP the last product. The Km values estimated are 43 ± 7 μM for Mg-ATP and 12 ± 3 μM for phosphomevalonate, with a Vmax of 51 ± 2 μmol minâ1 mg of proteinâ1.
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Authors
Jaime Eyzaguirre, David Valdebenito, Emilio Cardemil,