Drugs online research references
Antimicrob Agents Chemother. 1996 Sep;40(9):2075-9.
Specific interaction between beta-lactams and soluble penicillin-binding protein 2a from methicillin-resistant Staphylococcus aureus: development of a chromogenic assay.
Roychoudhury S, Kaiser RE, Brems DN, Yeh WK.
Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, Indiana 46285, USA.
We investigated the enzymatic acylation of penicillin-binding protein 2a (PBP 2a) from methicillin-resistant Staphylococcus aureus by beta-lactams. Using a purified, soluble form of the protein (PBP 2a'), we observed beta-lactam-induced in vitro precipitation following first-order kinetics with respect to protein concentration. We used electrospray mass ionization spectrometry to show that the protein precipitate predominantly contained PBP 2a', with the beta-lactam bound to it in a 1:1 molar ratio. Using nitrocefin, a chromogenic beta-lactam, we confirmed the correlation between PBP 2a' precipitation and its beta-lactam-dependent enzymatic acylation by monitoring the absorbance associated with the precipitate. Finally, dissolving the precipitate in urea, we developed a simple in vitro chromogenic assay to monitor beta-lactam-dependent enzymatic acylation of PBP 2a'. This assay represents a significant improvement over the traditional radioactive penicillin-binding assay.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8878584&dopt=Abstract
FEBS Lett. 1996 Sep 23;394(1):31-3.
Phenoxymethylpenicillin amidohydrolases from Penicillium chrysogenum.
Whiteman PA, Abraham EP.
The Sir William Dunn School of Pathology, Oxford, UK.
A phenoxymethylpenicillin amidohydrolase which hydrolyses phenoxymethylpenicillin to 6-aminopenicillanic acid (6-APA) has been isolated from two species of Penicillium chrysogenum. The amidohydrolase had a molecular mass of approx. 42 kDa. Its activity with benzylpenicillin as substrate was only 1.5% of that with phenoxymethylpenicillin and it was inhibited by its products. No penicillin formation from 6-APA and phenoxyacetyl or phenylacetyl coenzyme A was observed. The enzyme is thus distinct from the phenylacetyl coenzyme A:6-APA acyltransferase, which also has amidohydrolase activity and is involved in the final stages of the biosynthesis of penicillins.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8925921&dopt=Abstract
Hindustan Antibiot Bull. 1995 Feb-Nov;37(1-4):9-15.
Purification and characterization of extracellular penicillin V acylase from Fusarium sp. SKF 235.
Sudhakaran VK, Shewale JG.
Research and Development, Hindustan Antibiotics Ltd., Pimpri, Pune, India.
Penicillin V acylase from Fusarium sp. SKF 235 culture filtrate was purified to homogeneity. The enzyme was a glycoprotein and composed of single polypeptide chain with molecular weight of 83,200 Daltons. The pH and temperature optima were 6.5 and 55 degrees C, respectively. The KM for penicillin V was 10 mM but the enzyme was inhibited by penicillin V at concentrations above 50 mM. Products of reaction, 6-aminopenicillanic acid and phenoxyacetic acid inhibited the enzyme competitively and noncompetitively with Ki values of 18 mM and 45 mM, respectively. The enzyme specifically hydrolyzed penicillin V, cephalosporanic acid V and penicillin V sulphoxide. Other phenoxy acetyl amides studied were not hydrolysed. It is proposed that phenoxyacetyl moiety alone is not recognized by the penicillin V acylase and in addition, the beta-lactam structure contributes in formation of enzyme-substrate complex.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8972136&dopt=Abstract
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