Singlet oxygen inactivates protein tyrosine phosphatase-1B by oxidation of the active site cysteine

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Protein tyrosine phosphatase 1B (PTP1B) is a validated target for the treatment of type 2 diabetes and obesity. The discovery of selective inhibitors with drug-like properties has proven to be challenging because there are [about]80 PTP family members that share a similar and positively charged active site. To overcome these challenges, we have pursued two novel approaches for the covalent inactivation of PTP1B. Exo-affinity labeling agents exploit covalent reactions with amino acids outside the enzyme active site to gain both affinity and selectivity. We prepared several affinity labeling agents using a 12-step convergent synthesis. Enzyme assays revealed that some of these agents are capable of inactivating the enzyme by covalent modification. In another project, we prepared a low molecular weight mimic of the oxidized form of PTP1B that is generated in cells, during insulin signaling events. Seeking molecules capable of covalent capture of oxidized PTP1B, we treated this chemical model with several carbon nucleophiles, such as 1,3-diketones and sulfone-stabilized carbon anions. These carbon nucleophiles readily reacted with the model compound, under mild conditions to give stable adducts. Inactivation experiments revealed that 1,3-diketones are capable of inactivating the oxidized PTP1B at micromolar concentrations.

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Nitrate in the active site of protein tyrosine phosphatase 1B is a putative mimetic of the transition state

Acta Crystallographica Section D Biological Crystallography ◽

10.1107/s1399004713031052 ◽

2014 ◽

Vol 70 (2) ◽

pp. 565-571 ◽

Cited By ~ 2

Author(s):

Peter W. Kenny ◽

Janet Newman ◽

Thomas S. Peat

Keyword(s):

Protein Tyrosine Phosphatase ◽

Active Site ◽

Tyrosine Phosphatase ◽

Nitrate Anion ◽

Protein Tyrosine Phosphatase 1B ◽

Tyrosine Residue ◽

X Ray ◽

Protein Tyrosine ◽

Catalytic Cysteine ◽

Close Contacts

The X-ray crystal structure of the complex of protein tyrosine phosphatase 1B with nitrate anion has been determined and modelled quantum-mechanically. Two protomers were present in the structure, one with the mechanistically important WPD loop closed and the other with this loop open. Nitrate was observed bound to each protomer, making close contacts with the S atom of the catalytic cysteine and a tyrosine residue from a crystallographically related protomer.

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Identification of the oxidation states of the active site cysteine in a recombinant protein tyrosine phosphatase by electrospray mass spectrometry using on-line desalting

Rapid Communications in Mass Spectrometry ◽

10.1002/(sici)1097-0231(19981030)12:20<1457::aid-rcm346>3.0.co;2-a ◽

1998 ◽

Vol 12 (20) ◽

pp. 1457-1462 ◽

Cited By ~ 11

Author(s):

Jon P. DeGnore ◽

Simone König ◽

William C. Barrett ◽

P. Boon Chock ◽

Henry M. Fales

Keyword(s):

Mass Spectrometry ◽

Recombinant Protein ◽

Protein Tyrosine Phosphatase ◽

Active Site ◽

Electrospray Mass Spectrometry ◽

Tyrosine Phosphatase ◽

Oxidation States ◽

Protein Tyrosine ◽

Active Site Cysteine ◽

On Line

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Structure-Based Optimization of Protein Tyrosine Phosphatase 1B Inhibitors: From the Active Site to the Second Phosphotyrosine Binding Site

Journal of Medicinal Chemistry ◽

10.1021/jm0702478 ◽

2007 ◽

Vol 50 (19) ◽

pp. 4681-4698 ◽

Cited By ~ 81

Author(s):

Douglas P. Wilson ◽

Zhao-Kui Wan ◽

Wei-Xin Xu ◽

Steven J. Kirincich ◽

Bruce C. Follows ◽

...

Keyword(s):

Binding Site ◽

Protein Tyrosine Phosphatase ◽

Active Site ◽

Tyrosine Phosphatase ◽

Protein Tyrosine Phosphatase 1B ◽

Protein Tyrosine

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