Related Experiment Videos
Suicide inactivation of human prostatic acid phosphatase and a phosphotyrosine phosphatase
1Department of Chemistry, University of British Columbia, Vancouver, Canada.
Abstract:
4-Difluoromethylphenyl bis(cyclohexylammonium) phosphate was synthesized in 4 steps starting from dibenzyl phosphite and shown to be a time-dependent suicide inactivator of human prostatic acid phosphatase and the SHP protein tyrosine phosphatase. The inactivation of human prostatic acid phosphatase followed pseudo-first-order kinetics with inactivation constants of Ki = 1.0 mM; ki = 0.15 min-1 (t1/2 = 4.6 min at saturation). Phenyl phosphate protected the enzyme against inactivation, indicating that inactivation occurs in the active site. The inactivation of SHP also followed pseudo-first-order kinetics, with a t1/2 = approximately 15 min in the presence of 8.2 mM inhibitor. The mechanism of inactivation likely involves the enzymatic release of difluoromethyl phenol which rapidly eliminates fluoride, generating a quinone methide. This potent electrophile then reacts with residues at the active site of the enzyme. This inhibitor and peptidic derivatives thereof have excellent potential for selective inactivation and labeling of protein tyrosine phosphatases.
Insights
A novel phosphate compound selectively inactivates key enzymes like human prostatic acid phosphatase and SHP protein tyrosine phosphatase. This discovery offers potential for targeted enzyme inhibition and labeling in research.
Area of Science:
- Biochemistry
- Enzymology
- Medicinal Chemistry
Background:
- Protein tyrosine phosphatases (PTPs) are crucial enzymes involved in cellular signaling.
- Dysregulation of PTPs is implicated in various diseases, including cancer.
- Developing selective inhibitors for PTPs is a significant therapeutic goal.
Purpose of the Study:
- To synthesize and characterize a novel inhibitor targeting human prostatic acid phosphatase and SHP protein tyrosine phosphatase.
- To investigate the mechanism of enzyme inactivation by the synthesized compound.
- To explore the potential of this inhibitor and its derivatives for selective enzyme targeting.
Main Methods:
- Synthesis of 4-Difluoromethylphenyl bis(cyclohexylammonium) phosphate in four steps.
- Enzyme kinetics studies to determine inactivation constants (Ki, ki) and half-lives (t1/2).
- Competitive inhibition assay using phenyl phosphate to probe the active site interaction.
Main Results:
- The synthesized compound acts as a time-dependent suicide inactivator of both human prostatic acid phosphatase and SHP.
- Inactivation followed pseudo-first-order kinetics, with specific constants determined for each enzyme.
- Evidence suggests inactivation occurs at the active site, with phenyl phosphate offering protection.
Conclusions:
- The novel inhibitor demonstrates potent and selective inactivation of target phosphatases.
- The proposed mechanism involves enzymatic release of a reactive intermediate, a quinone methide.
- This inhibitor and its derivatives hold promise for selective protein tyrosine phosphatase inactivation and labeling.