Use of fluorinated tyrosine phosphates to probe the substrate specificity of the low molecular weight phosphatase activity of calcineurin.
Calcineurin, a calmodulin-activated protein phosphatase, is known to dephosphorylate certain low molecular weight phosphate esters. The low molecular weight phosphatase activity of calcineurin has been studied by utilizing tyrosine phosphate derivatives. Kinetic studies suggest that the substrate specificity is dependent upon the electronic nature of the substrate in contrast to results obtained with alkaline phosphatase from Escherichia coli. Comparison of calcineurin and acid-catalyzed hydrolyses indicates a 1:1 correlation between the rate constants for the two processes. This correlation and other model studies have been utilized to provide insight into the chemical mechanism of calcineurin. Possible chemical mechanisms for calcineurin are discussed.
Martin
B
B
Pallen
C J
CJ
Wang
J H
JH
Graves
D J
DJ
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002417:Cattle; D004926:Escherichia coli / Q000201:enzymology; D006868:Hydrolysis; D007700:Kinetics; D008970:Molecular Weight; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D019000:Phosphotyrosine; D013379:Substrate Specificity; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D002148:Calmodulin-Binding Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D000469:Alkaline Phosphatase; D010744:Phosphoric Monoester Hydrolases