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The β-lactam ring is part of the core structure of several antibiotic families, the principal ones being the penicillins, cephalosporins, carbapenems, and monobactams, which are, therefore, also called β-lactam antibiotics.
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β-lactam and ring
A β-lactam ( beta-lactam ) ring, is a four-membered lactam.
That is, position 1 is always adjacent to the β-carbon of β-lactam ring.
The The numbering continues clockwise from position one until the β-carbon of β-lactam is reached, at which point numbering continues counterclockwise around the lactam ring to number the remaining to carbons.
This strain is further increased by fusion to a second ring, as found in most β-lactam antibiotics.
β-lactam ring in red.
The lactamase enzyme breaks the β-lactam ring open, deactivating the molecule's antibacterial properties.
However, the usefulness of the β-lactam ring was such that related antibiotics, including the mecillinams, the carbapenems and, most important, the cephalosporins, still retain it at the center of their structures.
Bacteria often develop resistance to β-lactam antibiotics by synthesizing a β-lactamase, an enzyme that attacks the β-lactam ring.
By definition, all β-lactam antibiotics have a β-lactam ring in their structure.
If the bacterium produces the enzyme β-lactamase or the enzyme penicillinase, the enzyme will hydrolyse the β-lactam ring of the antibiotic, rendering the antibiotic ineffective.
While the ring closure in penams and cephems is between positions 1 and 4 of the β-lactam and is oxidative, the clavams and carbapenems have their rings closed by two-electron processes between positions 1 and 2 of the ring.
In clavams, the β-lactam is formed prior to the second ring ; in carbapenems, the β-lactam ring is closed second in sequence.
The biosynthesis of the β-lactam ring of tabtoxin mirrors that of the clavams and carbapenems.
Staphylococcal resistance to penicillin is mediated by penicillinase ( a form of β-lactamase ) production: an enzyme that cleaves the β-lactam ring of the penicillin molecule, rendering the antibiotic ineffective.
* A group including Dorothy Hodgkin publish the three-dimensional molecular structure of penicillin, demonstrating that it contains a β-lactam ring.
Prefixes indicate how many carbon atoms ( apart from the carbonyl moiety ) are present in the ring: β-lactam ( 2 carbon atoms outside the carbonyl, 4 ring atoms in total ), γ-lactam ( 3 and 5 total ), δ-lactam ( 4 and 6 total ).
β-lactam and is
The simplest β-lactam possible is 2-azetidinone.
This trend is due to the amide character of the β-lactam being reduced by the aplanarity of the system.
Pain and inflammation at the injection site is also common for parenterally administered β-lactam antibiotics.
Nevertheless, the risk of cross-reactivity is sufficient to warrant the contraindication of all β-lactam antibiotics in patients with a history of severe allergic reactions ( urticaria, anaphylaxis, interstitial nephritis ) to any β-lactam antibiotic.
As a result, the bactericidal action of β-lactam antibiotics is further enhanced.
The first is known as " Woodward's parameter ", h, and is the height ( in angstroms ) of the pyramid formed by the nitrogen atom of the β-lactam as the apex and the three adjacent carbon atoms as the base.
The second is called " Cohen's parameter ", c, and is the distance between the carbon atom of the carboxylate and the oxygen atom of the β-lactam carbonyl.
For example, Augmentin ( FGP ) is made of amoxicillin, a β-lactam antibiotic, and clavulanic acid, a β-lactamase inhibitor.
However, in all cases where infection with β-lactamase-producing bacteria is suspected, the choice of a suitable β-lactam antibiotic should be carefully considered prior to treatment.
In particular, choosing appropriate β-lactam antibiotic therapy is of utmost importance against organisms with inducible β-lactamase expression.
If β-lactamase production is inducible, then failure to use the most appropriate β-lactam antibiotic therapy at the onset of treatment will result in induction of β-lactamase production, thereby making further efforts with other β-lactam antibiotics more difficult.
β-lactam and core
To date, two distinct methods of biosynthesizing the β-lactam core of this family of antibiotics have been discovered.
Next, a β-lactam synthetase uses ATP to form the β-lactam and the saturated carbapenam core.
β-lactam and structure
However, the similarity in chemical structure allows the molecule to interact with the enzyme β-lactamase secreted by certain bacteria to confer resistance to β-lactam antibiotics.
β-lactam and antibiotic
β-Lactam antibiotics ( beta-lactam antibiotics ) are a broad class of antibiotics, consisting of all antibiotic agents that contains a β-lactam nucleus in their molecular structures.
Immunologically mediated adverse reactions to any β-lactam antibiotic may occur in up to 10 % of patients receiving that agent ( a small fraction of which are truly IgE-mediated allergic reactions, see amoxicillin rash ).
A Jarisch-Herxheimer reaction may occur after initial treatment of a spirochetal infection such as syphilis with a β-lactam antibiotic.
Two structural features of β-lactam antibiotics have been correlated with their antibiotic potency.
The treatment of choice for S. aureus infection is penicillin ; in most countries, though, penicillin resistance is extremely common, and first-line therapy is most commonly a penicillinase-resistant β-lactam antibiotic ( for example, oxacillin or flucloxacillin ).
Penicillin, considered the most famous antibiotic, is a β-lactam antibiotic.
Fourth generation of cephalosporin, a β-lactam antibiotic Cefepime
β-lactam and principal
In addition, they are generally resistant to the typical bacterial enzyme, β-lactamase, which is one of the principal β-lactam resistance mechanisms of bacteria.
β-lactam and being
h corresponds to the strength of the β-lactam bond with lower numbers ( more planar ; more like ideal amides ) being stronger and less reactive.
β-lactam and penicillins
All penicillins are β-lactam antibiotics and are used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms.
These agents have the broadest antibacterial spectrum compared to other β-lactam classes such as penicillins and cephalosporins.
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