Beta-lactam antibiotics are used to treat a broad spectrum of Gram-positive and Gram-negative bacteria.
β-lactam antibiotics target the penicillin-binding proteins (PBPs) – a group of enzymes found attached in the cell membrane, which are involved in the cross-linking of the bacterial cell wall. The β-lactam ring portion of this group of antibiotics binds to these different PBPs, rendering them unable to perform their role in cell wall synthesis. This then leads to death of the bacterial cell due to osmotic instability or autolysis.
The most effective way for bacteria to counteract these chemicals has been by producing β-lactamases, enzymes that inactivate the drugs by hydrolyzing the β-lactam ring.
|Product Number||Product Name|
|A-1414||Ampicillin Sodium Salt|
|A-1415||Ampicillin Sodium Salt Solution (100 mg/mL)|
|C-1385||Carbenicillin Disodium Salt|
|C-1386||Carbenicillin Disodium Salt Solution (100 mg/mL)|
|E-2497||Ertapenem Sodium Salt|
|L-2467||Beta Lactamase – Broad Spectrum|
|O-2579||Oxacillin Sodium Salt|
|P-1681||Penicillin G Potassium|
|P-2831||Penicillin G Sodium|
|T-2721||Ticarcillin Disodium Salt|
Classification of Beta-Lactamases
β-lactamases are classified under two categories. The first one is dependent on the biochemical and functional characteristics of the enzyme. The second is based on the enzyme’s molecular structure.
For the functional classification, several criteria are used including the spectrum of antimicrobial substrate profile, enzyme inhibition profile, hydrolysis rate, binding affinity, isoelectric focusing, protein molecular weight, and amino acid composition.
The molecular classification of β-lactamases is based on the nucleotide and amino acid sequences in these enzymes. Four classes of β-lactamases are recognized (A-D), correlating with the functional classification. Classes A, C, and D act by a serine-based mechanism, whereas class B or metallo β-lactamases need zinc for their action.
Out of the four classes of β-lactamase, class A lactamases have been used as versatile scaffolds to create hybrid enzymes. These are referred to as β-lactamase hybrid proteins (BHPs). In this application, an exogenous peptide, protein or fragment is inserted at various permissive portions. BHPs are designed to:
- Create bifunctional proteins
- Produce and characterize proteins which are otherwise difficult to express
- Determine the epitope of specific antibodies
- Generate antibodies against nonimmunogenic epitopes
- Better understand structure/functional relationship of proteins.
The two class A β-lactamases that have been extensively used as model proteins to insert exogenous polypeptides are BlaP from Bacillus licheniformis 749/C and TEM-1. TEM-1 is the most commonly found β-lactamase in Gram-negative bacteria. These two enzymes are secreted by bacteria in the external environment and expressed in the periplasmic space to inactivate β-lactam antibiotics. About 20-40% of the amino acids are identical and homologous between these two serine-active β-lactamases.
Beta-Lactamase in the Future
In addition to the above-mentioned applications, there are other proposed applications, including:
- BHPs could be used as biosensors and in affinity chromatography, drug screening, and drug targeting
- They are also of special interest to better understand more fundamental aspects of protein evolution and structure/function relationships.
- Kong, Kok-Fai, et al. “Beta-Lactam Antibiotics: from Antibiosis to Resistance and Bacteriology.” APMIS, vol. 118, no. 1, Jan. 2010, pp. 1–36.
- Huynen, Céline, et al. “Class A β-Lactamases as Versatile Scaffolds to Create Hybrid Enzymes: Applications from Basic Research to Medicine.” BioMed Research International, vol. 16, no. 1, 22 Aug. 2013.