Penicillin-binding proteins- off page promotion word (1)

1. Penicillin-binding proteins Penicillin-binding proteins (PBPs) are a group of proteins that are characterized by their affinity for and binding of penicillin. They are a normal constituent of many bacteria; the name just reflects the way by which the protein was discovered. All β-lactam antibiotics (except for tabtoxinine-β-lactam, which inhibits glutamine synthetase) bind to PBPs, which are essential for bacterial cell wall synthesis. PBPs are members of a subgroup of enzymes called transpeptidases. Specifically, PBPs are DD-transpeptidases. PBPs bind to β-lactam antibiotics because they are similar in chemical structure to the modular pieces that form the peptidoglycan.When they bind to penicillin, the β-lactam amide bond is ruptured to form a covalent bond with the catalytic serine residue at the PBPs active site. This is an irreversible reaction and inactivates the enzyme. There has been a great deal of research into PBPs because of their role in antibiotics and resistance. Bacterial cell wall synthesis and the role of PBPs in its synthesis is a very good target for drugs of selective toxicity because the metabolic pathways and enzymes are unique to bacteria.[10] Resistance to antibiotics has come about through overproduction of PBPs and formation of PBPs that have low affinity for penicillins (among other mechanisms such as lactamase production). These experiments change the structure of PBP by adding different amino acids into the protein, allowing for new discovery of how the drug interacts with the protein. Research on PBPs has led to the discovery of new semi-synthetic β-lactams, wherein altering the side-chains on the original penicillin molecule has increased the affinity of PBPs for penicillin, and, thus, increased effectiveness in bacteria with developing resistance.