Boron-containing small molecules for inhibiting activity of a receptor-like protein tyrosine phosphatase

A method is disclosed for altering the redox equilibrium of a transmembrane receptor-like protein tyrosine phosphatase (RPTP), particularly a type IIa RPTP, by chemically modulating the activity through contact of such an enzyme with a diaryl boron compound that preferentially reacts with an RPTP in an oxidized state (CyS-OH). This redox modulation is most readily observed and put to use by assaying the inhibition of the phosphatase activity of the RPTP. Such an assay can be carried out on an enzyme in vitro or by contacting the enzyme in a living organism (in vivo). A useful diaryl boron compound corresponds in structure to Formula I in which Ar-1, Ar-2, R 1 , R 2 , R 3 and R 4 are defined within. A pharmaceutical composition containing a useful diaryl boron compound is also disclosed, as are particularly preferred diaryl boron compounds.