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The other type of beta-lactamase is of the metallo type ("type B"). Metallo-beta-lactamases (MBLs) need metal ion(s) (1 or 2 Zn 2+ ions [2]) on their active site for their catalytic activities. [3] The structure of the New Delhi metallo-beta-lactamase 1 is given by 6C89. It resembles a RNase Z, from which it is thought to have evolved.
Similarly, it has been demonstrated that zinc chelators can inhibit the hydrolytic activity of metallo-β-lactamases against β-lactam antibiotics, restoring the activity of the latter. [6] Metallo-beta-lactamases are important enzymes because they are involved in the breakdown of antibiotics by antibiotic-resistant bacteria. [7]
CBMAR (Comprehensive β-lactamase Molecular Annotation Resource) is a database focused on the annotation and discovery of novel beta-lactamase genes and proteins in bacteria. [1] Beta-lactamases are characterized on CBMAR using the Ambler Classification system. [2] CBMAR organizes beta-lactamases according to their classes: A, B, C, and D.
A lactam is a cyclic amide, and beta-lactams are named so because the nitrogen atom is attached to the β-carbon atom relative to the carbonyl. The simplest β-lactam possible is 2-azetidinone. β-lactams are significant structural units of medicines as manifested in many β-lactam antibiotics . [ 2 ]
Two zinc ions present in the active binding site. NDM-1 functions through two zinc ions present in the active site that cause hydrolysis of the beta-lactams, rendering them ineffective. Experimental data has shown that zinc chelators can prevent the hydrolysis of beta-lactams mediated by metallo-beta-lactamases. [14]
The β-lactam core structures. (A) A penam.(B) A carbapenam.(C) An oxapenam.(D) A penem.(E) A carbapenem.(F) A monobactam.(G) A cephem.(H) A carbacephem.(I) An oxacephem. This is a list of common β-lactam antibiotics—both administered drugs and those not in clinical use—organized by structural class.
For example, Augmentin (FGP) is made of amoxicillin (a β-lactam antibiotic) and clavulanic acid (a β-lactamase inhibitor). The clavulanic acid is designed to overwhelm all β-lactamase enzymes, and effectively serve as an antagonist so that the amoxicillin is not affected by the β-lactamase enzymes. Another β-lactam/β-lactamase inhibitor ...
The structure of the active site in carbonic anhydrases is well known from a number of crystal structures. It consists of a zinc ion coordinated by three imidazole nitrogen atoms from three histidine units. The fourth coordination site is occupied by a water molecule. The coordination sphere of the zinc ion is approximately tetrahedral.