Inhibition protein tyrosine phosphatases by an oxovanadium glutamate complex, Na2[VO(Glu)2(CH3OH)](Glu = glutamate)
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The insulin-sensitizing effect of vanadium complexes has been linked to their ability to inhibit protein tyrosine phosphatases (PTPs). Considering that vanadium complexes may exchange in vivo with amino acids, forming in situ vanadium–amino acid complexes, we have synthesized and characterized an oxovanadium glutamate complex, Na2[V(IV)O(Glu)2(CH3OH)]H2O (1·H2O). The complex showed potent inhibition against four human PTPs (PTP1B, TCPTP, HePTP, and SHP-1) with IC50 in the 0.21–0.37 μM ranges. Fluorescence titration studies suggest that the complex binds to PTP1B with the formation of a 2:1 complex. Enzyme kinetics analysis using Lineweaver–Burk plots indicates a typical competitive inhibition mode.