Inhibition of protein tyrosine phosphatase 1B and alkaline phosphatase by bis(maltolato)oxovanadium (IV).
Vanadate has been recognized as a specific and potent phosphatase inhibitor since its structure is similar to that of phosphate. In this study, we measured the inhibition of glutathione S-transferase-tagged protein tyrosine phosphatase 1B (GST-PTP1B) and alkaline phosphatase (ALP) by the insulin enhancing compounds, bis(maltolato)oxovanadium(IV) (BMOV). The results showed that the activity of GST-PTP1B was reversibly inhibited by solutions of BMOV with an IC(50) value of 0.86+/-0.02 microM. Steady state kinetic studies showed that inhibition of GST-PTP1B by BMOV was of a mixed competitive and noncompetitive type. In addition, incubation of GST-PTP1B with BMOV showed a time-dependent biphasic inactivation of the protein. On the other hand, the inhibitory behavior of BMOV on ALP activity was reversible and competitive with an IC(50) value of 32.1+/-0.6 microM. Incubation with BMOV did not show biphasic inactivation of ALP. The reversible inhibition of GST-PTP1B by BMOV is more potent than that of ALP, but solutions of BMOV inhibited both enzymes. This data support the suggestion that mechanisms for the inhibitory effects of BMOV on GST-PTP1B and ALP are very different.
Li
Ming
M
College of Life Sciences, Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
Ding
Wenjun
W
Baruah
Bharat
B
Crans
Debbie C
DC
Wang
Ruilin
R
D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1 / Q000037:antagonists & inhibitors*; D011753:Pyrones / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors; D014638:Vanadates / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*
D007328:Insulin; D011753:Pyrones; D011993:Recombinant Fusion Proteins; C074212:bis(maltolato)oxovanadium(IV); D014638:Vanadates; D000469:Alkaline Phosphatase; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1