Mapping the Active Site of AmpC β-Lactamase
Antibiotic resistance has emerged as the leading public health crisis of the 21st century. The most prevalent resistance mechanism to commonly prescribed b-lactam antibiotics like penicillin is the b–lactamase. These enzymes break apart the lactam ring that is crucial for the antibiotic to be effective. One way to overcome this resistance is to block the activity of this enzyme. Boronic acids are a class of molecules known to inhibit the activity of the class C b–lactamase AmpC. Inhibition is achieved through specific interactions between the boronic acid and amino acids in the active site of AmpC, thus preventing the destruction of the b-lactam. In this study, we chose four boronic acids that differed in size and chemical functionality to investigate specific molecular interactions in the active site of AmpC. Each boronic acid was tested experimentally for inhibition of AmpC in kinetic assays to determine IC50 and KI values, which indicate how effective a molecule is at blocking AmpC activity. All inhibitors were co-crystallized in complexes with AmpC, and electron density for these inhibitors was visualized using X-ray crystallography. Data obtained from these complexes provides information on binding site interactions in the active site and may be useful for future drug discovery against AmpC.
Faculty Mentor: Rachel Powers
Rachel presented at the 234th American Chemical Society Fall National Meeting and Exposition August 19-23, 2007 in Boston, MA.
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