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Hot Biological Catalysis: Isothermal Titration Calorimetry to Characterize Enzymatic Reactions
Published on: April 4, 2014
Isotope effects in the study of enzymatic phosphoryl transfer reactions
1Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA. hengge@cc.usu.edu
Abstract:
Protein-tyrosine phosphatases and serine/threonine protein phosphatases utilize very different catalytic machinery to catalyze phosphoryl transfer reactions. Tyrosine is a better leaving group than serine or threonine, having a pK(a) more than three units lower. Has the difference in the catalytic machinery used by these enzyme families evolved as a result of the difference in the lability of their substrates? Are the transition states for phosphoryl transfer similar for the two classes of enzymes? This review summarizes what has been learned from kinetic isotope effects about the nature of enzymatic phosphoryl transfer, and how the enzymatic mechanisms compare to uncatalyzed phosphoryl transfer reactions.
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