Abstract

β-lactamases are the most widespread cause of bacterial resistance to β-lactam antibiotics, such as the penicillins and cephalosporins, and the mechanisms of these enzymes are intensely studied. The first β-lactamase was identified in an isolate of Escherichia coli in 1940. Many of the gram-negative bacteria possess a naturally occurring, chromosomally mediated β-lactamase, which probably assists the bacteria in finding a niche when faced with competition from other bacteria that naturally produce β-lactams. β-lactamases are classified into two major types on the basis of the main component of the active site: serineβ-lactamases and metallo-β-lactamases. Serineβ-lactamases are further classified into three classes: class A, C, and D; i.e.,metalloβ-lactamase is classified into class B. As is well known, the catalytic mechanism of serineβ-lactamases involves acylation and deacylation. In this paper, we have investigated the mechanisms of class A β-lactamase, most of which have extended spectrum β-lactamases belonging to that of the other classes B,C, and D β-lactamase. (Korean J UTII 2012;7:89-98)

• Keywords: β-Lactamases, Mechanism of action

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