Inactivation of TEM-1 beta-lactamase by 6-acetylmethylenepenicillanic acid
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Abstract:
6-Acetylmethylenepenicillanic acid is a new kinetically irreversible inhibitor of various beta-lactamases. Interaction between 6-acetylmethylenepenicillanate and purified TEM-1 beta-lactamase during the inactivation process was investigated. 6-Acetylmethylenepenicillanate inhibited the enzyme in a second-order fashion with a rate constant of 0.61 microM-1 . S-1. The apparent inactivation constant decreased in the presence of increasing concentrations of the substrate benzylpenicillin. Native enzyme (pI 5.4) was converted into two inactive forms with pI 5.25 and 5.15, the latter form being transient and readily converted into the more stable form with pI 5.15. Even a 50-fold excess of inhibitor over enzyme did not produce any other inactivated species of the enzyme. All the results obtained suggest that 6-acetylmethylenepenicillanate is a potent irreversible and active-site-directed inhibitor of TEM-1 beta-lactamase.
Insights
6-Acetylmethylenepenicillanic acid effectively inhibits TEM-1 beta-lactamase irreversibly. This potent inhibitor targets the enzyme's active site, offering a new strategy against beta-lactamase resistance.
Area of Science:
- Biochemistry
- Enzymology
- Drug Discovery
Background:
- Beta-lactamases are enzymes that confer bacterial resistance to beta-lactam antibiotics.
- Development of novel inhibitors is crucial to combat antibiotic resistance.
Purpose of the Study:
- To investigate the interaction between 6-acetylmethylenepenicillanate and purified TEM-1 beta-lactamase.
- To characterize the mechanism of inactivation by this novel inhibitor.
Main Methods:
- Enzyme kinetics studies using purified TEM-1 beta-lactamase.
- Analysis of enzyme inactivation rates and substrate dependency.
- Isoelectric focusing to characterize modified enzyme forms.
Main Results:
- 6-Acetylmethylenepenicillanate demonstrated kinetically irreversible inhibition of TEM-1 beta-lactamase.
- Inhibition followed second-order kinetics with a rate constant of 0.61 microM-1 . S-1.
- The inhibitor converted the native enzyme (pI 5.4) into inactive forms with pI 5.25 and 5.15.
Conclusions:
- 6-Acetylmethylenepenicillanate is a potent, irreversible, active-site-directed inhibitor of TEM-1 beta-lactamase.
- The observed inactivation mechanism suggests a specific interaction with the enzyme's catalytic site.
- This compound holds potential as a therapeutic agent against beta-lactamase-producing bacteria.