BLAD ß-Lactmase Database
A comprehensive database of widely circulated ß-Lactamases
Welcome to ß-Lactamase
Beta-lactamases are enzymes produced by some bacteria and are responsible for their resistance to beta-lactam antibiotics like penicillins, cephamycins, and carbapenems (ertapenem) (Cephalosporins are relatively resistant to beta-lactamase). These antibiotics have a common element in their molecular structure: a four-atom ring known as a beta-lactam.
TEM beta-lactamase (Class A)
TEM beta-lactamases (class A)TEM-1 is the most commonly-encountered beta-lactamase in Gram-negative bacteria. Up to 90% of ampicillin resistance in E. coli is due to the production of TEM-1. Also responsible for the ampicillin and penicillin resistance that is seen in H. influenzae and N. gonorrhoeae in increasing numbers. Although TEM-type beta-lactamases are most often found in E. coli and K. pneumoniae, they are also found in other species of Gram-negative bacteria with increasing frequency. The amino acid substitutions responsible for the ESBL phenotype cluster around the active site of the enzyme and change its configuration, allowing access to oxyimino-beta-lactam substrates. Opening the active site to beta-lactam substrates also typically enhances the susceptibility of the enzyme to b-lactamase inhibitors, such as clavulanic acid. Single amino acid substitutions at positions 104, 164, 238, and 240 produce the ESBL phenotype, but ESBLs with the broadest spectrum usually have more than a single amino acid substitution. Based upon different combinations of changes, currently 140 TEM-type enzymes have been described. TEM-10, TEM-12, and TEM-26 are among the most common in the United States.
Beta-lactam antibiotics are typically used to treat a broad spectrum of Gram-negative bacteria. Beta-lactamases produced by Gram-negative organisms are usually secreted.
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Copyright © 2012 Dr. Asad U Khan All rights reserved
Interdisciplinary Biotechnology Unit
Aligarh Muslim University, Aligarh-202001
Uttar Pradesh, India