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==='''Mechanism of Action of B-Lactam Antibiotics'''=== | ==='''Mechanism of Action of B-Lactam Antibiotics'''=== | ||
The B-Lactam antibiotics inhibit bacterial cell growth by irreversibly inhibiting TP's and, therefore, bacterial cell wall sythesis. Specifically, B-Lactams are molecular mimics of a portion of the peptidoglycan polymer, namely the D-Ala-D-Ala moiety, which is the normal TP enzymatic substrate(Figure 4). As a result, bacterial TP enzymes are "tricked" into reacting with B-Lactams. Additionally, the B-Lactams are very reactive molecules due to their B-lactam ring, and readily react with the TP active site serine residue and sterically block the active site preventing the entry of nucleophiles that regenerate the active site serine residue such as the pentaglycine chain or water. | The B-Lactam antibiotics inhibit bacterial cell growth by irreversibly inhibiting TP's and, therefore, bacterial cell wall sythesis. Specifically, B-Lactams are molecular mimics of a portion of the peptidoglycan polymer, namely the D-Ala-D-Ala moiety, which is the normal TP enzymatic substrate(Figure 4). As a result, bacterial TP enzymes are "tricked" into reacting with B-Lactams. Additionally, the B-Lactams are very reactive molecules due to their B-lactam ring, and readily react with the TP active site serine residue and sterically block the active site preventing the entry of nucleophiles that regenerate the active site serine residue such as the pentaglycine chain or water. | ||
[[Image:BLactamSchematic2.jpg|thumb| | [[Image:BLactamSchematic2.jpg|thumb|(a) The Beta-Lactam targets the active site, which normally is targeted by the pentaglycine. (b) The Beta-Lactam enters the active site and binds to the Ser403 thereby inhibiting the interaction between ser403 and the pentaglycine. (c) The pentaglycine leaves the active site.|550px]] | ||