Anti-Penicilline G monoclonal antibody, clone G84U84

Penicillin antibiotics are a class of widely used antibiotics, mainly used to treat various bacterial infections. These drugs can be divided into the following categories according to their chemical structure and antibacterial spectrum: 1. Natural penicillins: Penicillin G: For injection, mainly used to treat infections caused by streptococci, Treponema pallidum and some Gram-positive bacteria. Penicillin V: For oral use, suitable for mild to moderate infections, mainly targeting streptococci and some Gram-positive bacteria. 2. Broad-spectrum penicillins: Ampicillin: Used to treat a variety of infections of the respiratory tract, urinary tract, gastrointestinal tract and reproductive tract, with a wider antibacterial spectrum. Amoxicillin: Better oral absorption, commonly used to treat ear, nose and throat infections, bronchitis, urinary tract infections, etc. 3. Anti-penicillinase penicillins: Cloxacillin: Effective against Staphylococcus aureus, including some strains that produce penicillinase. Oxacillin: Similar to cloxacillin, it is used to treat penicillin-resistant staphylococcal infections. 4. Broad-spectrum amide penicillins: Piperacillin: Often used in combination with the β-lactamase inhibitor tazobactam, it is widely used for serious infections such as pneumonia, intra-abdominal infections and complicated urinary tract infections. Ticarcillin: Often used in combination with clavulanate, it is mainly used to treat serious Gram-negative infections. 5. β-lactamase inhibitor combination preparations: Amoxicillin/Clavulanate: Used to treat infections caused by resistant strains, including ear, nose and throat, lower respiratory tract, skin and urinary system infections. Piperacillin/Tazobactam: Used to treat complicated intra-abdominal infections, skin and soft tissue infections, and severe infections such as pneumonia. 6. Long-acting penicillins: Procaine Penicillin: Commonly used to prevent and treat syphilis, rheumatic fever, etc. Benzathine Penicillin: used to prevent recurrence of streptococcal infection and treat syphilis. 7. Other penicillins: Mezlocillin: mainly used for severe hospital-acquired infections and some Gram-negative bacterial infections. Piperacillin/Probenecid: increases the concentration of piperacillin in the body and is used for some serious infections.

Figure 1. Schematic representation of the mechanism of penicillin action. (Lobanovska M, et al. 2017)

Penicillin G is a white or off-white crystalline powder, slightly soluble in water, and easily soluble in dilute acid and alkaline solutions. The bicyclic structure of the β-lactam ring and the thiazole ring contains an active ester bond in the molecule, which is easily hydrolyzed by β-lactamase produced by bacteria, thereby losing its activity. Penicillin G is extracted from Penicillium chrysogenum by fermentation. After entering the human body, it is mainly metabolized in the liver and excreted from the body through the kidneys in the form of prototype or metabolites, with a short half-life. It is mainly used to treat various infections caused by sensitive bacteria, such as streptococcal infection, syphilis, anthrax, tetanus, etc. The drug causes bacterial death by inhibiting the synthesis of bacterial cell walls. Penicillin G needs to be injected (intramuscular or intravenous injection), has poor stability in acidic environments, and is not suitable for oral administration. Because it is easily destroyed by β-lactamase produced by bacteria, it is not effective against some drug-resistant strains. Most bacteria and chlamydia have some proteins on their cell membranes that can bind to penicillin and other β-lactam antibiotics, namely penicillin binding proteins (PBPs). These penicillin binding proteins present on the inner membrane of bacterial cells are the target molecules of penicillin. PBPs are membrane proteins with a molecular weight of 40,000 to 120,000. They are D,D-peptidases with catalytic activity that are indispensable in the synthesis of bacterial cell walls, such as transpeptidases, carboxypeptidases, endopeptidases, etc. They are proteins that play an important role in the growth of bacteria. The types and numbers of PBPs in different bacteria vary greatly. For example, Staphylococcus aureus has 4 PBPs, while Escherichia coli has at least 7. Penicillin and other β-lactam antibiotics, as structural analogs of PBPs substrates, competitively bind to the enzyme active site covalently, thereby inhibiting PBPs and interfering with the synthesis of bacterial cell walls to achieve the effect of killing bacteria. The sensitivity of bacteria to β-lactams is mainly due to the high affinity of their PBPs for this class of drugs. The affinity of various PBPs to different β-lactams is different. The high molecular weight PBPs (PBP1a and 1b) of Escherichia coli E contain transpeptidases related to peptidoglycan synthesis, while other PBPs are necessary to maintain the bacterial rod-shaped morphology and the formation of bacterial cell division septa. The most important PBP among PBPs is transpeptidase. The inhibition of transpeptidase can lead to the formation of spherical cells and rapid lysis. However, the inhibition of the activity of other PBPs may delay lysis (PBP2) or produce thread-shaped bacteria (PBP3). The amide bond in the penicillin β-lactam ring can acetylate and inactivate transpeptidase, thereby hindering the synthesis of bacterial cell wall mucopeptides. While causing defects in bacterial synthetic cell walls, it also inactivates autolytic enzyme inhibitors in the bacterial cell wall, activates autolytic enzymes, and leads to bacterial cell lysis.

Penicillin G (benzylpenicillin) has a benzyl side chain and is one of the five penicillins (X, F, G, K, double H) extracted from penicillin culture medium. It is commonly used because of its relatively stable chemical properties, strong antibacterial effect, high yield, low toxicity, and low price. Penicillin is an organic acid and is irritating, so its sodium or potassium salt is often used. Penicillin G is easily destroyed by gastric acid and digestive enzymes when taken orally, and its absorption is small and irregular, so it is not suitable for oral administration. It is usually injected intramuscularly and absorbed quickly and completely. Penicillin G is almost excreted rapidly in the urine in its original form, about 10% is excreted through glomerular filtration, and 90% is excreted through renal tubular secretion. Penicillin G has a strong antibacterial effect. Low concentrations inhibit bacteria during the bacterial reproduction period, and higher concentrations kill bacteria. It has high antibacterial activity against the following pathogens: 1. Most Gram-positive (G+) cocci, such as pneumococci, sensitive Staphylococcus aureus, Staphylococcus epidermidis, etc.; 2. G+ bacilli, such as diphtheria bacilli, tetanus bacilli, lactobacilli, etc.; 3. A few Gram-negative (G-) bacilli, such as influenza bacilli, pertussis Bordetella, etc.; 4. G- cocci, such as Neisseria meningitidis, sensitive Neisseria gonorrhoeae, etc.; 5. Spirochetes, actinomycetes, such as Treponema pallidum, Leptospira, Actinomycetes bovis, etc. It has no effect on fungi, protozoa, rickettsia, viruses, etc. Staphylococcus aureus, Neisseria gonorrhoeae, pneumococcus, Neisseria meningitidis, etc. are very likely to develop resistance to penicillin G.

Anti-Penicillin G monoclonal antibody
Penicillin G mAb
Pen G monoclonal antibody
Penicillin G-specific monoclonal antibody
Anti-benzylpenicillin monoclonal antibody
Penicillin G immunoglobulin