The catalytic mechanism of protein tyrosine phosphatases revisited.

Experimental and theoretical studies of the catalytic mechanism in protein tyrosine phosphatases and dual specific phosphatases are reviewed. The structural properties of these enzymes contributing to the efficient rate enhancement of phosphate monoester hydrolysis have been established during the last decade. There are, however, uncertainties in the interpretation of available experimental data that make the commonly assumed reaction mechanism somewhat doubtful. Theoretical calculations as well as analysis of crystal structures point towards an alternative interpretation of the ionisation state in the reactive complex.