Random Pathway Mechanism Involving Parallel One- and Two-Substrate Branches for Glyoxalase I from Yeast
Bengt Mannervik, Tamás Bartfai, Barbara Górna‐hall · Journal of Biological Chemistry · 1974
Abstract The steady state kinetic data of yeast glyoxalase I have been re-examined. Extension of the concentration ranges of the reactants reveal nonlinearities in v versus v/[A] and Dixon plots, which necessitate revision of a previous kinetic model (Bartfai, T., Ekwall, K., and Mannervik, B. (1973) Biochemistry 12, 387–391). The selection of the best mathematical model has been based on nonlinear regression methods and the results of inhibition studies involving S-substituted glutathione derivatives. A mechanism is proposed, which exhibits the unusual feature of alternative one- and two-substrate branches, the latter involving glutathione and methylglyoxal as the first and second substrates, and the former having their hemimercaptal adduct as the substrate.