Enzymatic synthesis of cephalosporins.

10/12/2017 · Enzymatic Synthesis of Penicillins and Cephalosporins by Penicillin ..
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Enzymatic synthesis of cephalothin by penicillin G …

In this study, we investigated the enzymatic synthesis of a semi-synthetic cephalosporin, cefadroclor, from 7-aminodesacetoxymethyl-3-chlorocephalosporanic acid (7-ACCA) and p-OH-phenylglycine methyl ester (D-HPGM) using immobilized penicillin G acylase (IPA) in organic co-solvents. Ethylene glycol (EG) was employed as a component of the reaction mixture to improve the yield of cefadroclor. EG was found to increase the yield of cefadroclor by 15–45%. An investigation of altered reaction parameters including type and concentration of organic solvents, pH of reaction media, reaction temperature, molar ratio of substrates, enzyme loading, and IPA recycling was carried out in the buffer mixture. The best result was a 76.5% conversion of 7-ACCA, which was obtained from the reaction containing 20% EG (v/v), D-HPGM to 7-ACCA molar ratio of 4:1 and pH 6.2, catalyzed by 16 IU mL−1 IPA at 20 °C for 10 h. Under the optimum conditions, no significant loss of IPA activity was found after seven repeated reaction cycles. In addition, cefadroclor exhibited strong inhibitory activity against yeast, Bacillus subtilis NX-2, and Escherichia coli and weaker activity against Staphylococcus aureus and Pseudomonas aeruginosa. Cefadroclor is a potential antibiotic with activity against common pathogenic microorganisms.

Search for Microorganisms Producing Cephalosporin Acylase and Enzymatic Synthesis of Cephalosporins
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Enzymatic synthesis of cephalothin by penicillin ..

Kluyvera citrophila has been selected as one of the strains for producing potent intracellular penicillin acylase activity with broad substrate specificity. Pseudomonas melanogenum produces a different type of penicillin acylase which is specific for α-amino acyl side chain precursors. Investigations of the conditions for cultivation of the bacteria and also of the enzymatic reactions revealed the optimal conditions suitable for the enzymatic synthesis of penicillins and cephalosporins by intact cells of these microorganisms. β-Lactamase, co-produced by the microorganisms under certain conditions, was deleted by alkaline treatment as well as by mutational techniques.

Modulation of the Microenvironment Surrounding the Active Site of Penicillin G Acylase Immobilized on Acrylic Carriers Improves the Enzymatic Synthesis of Cephalosporins
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Microorganisms were tested for production of cephalosporin acylase. Some bacteria showed strong acylase activity for all of cephalexin, cephaloridine, cephalotin, penicillin G and ampicillin. Some showed a rather specific activity for cephalexin. KY 3987 showed specific activity only for cephalexin and ampicillin which contain a side chain of D-phenylglycine. Most of these acylase-producing bacteria had the ability to synthesize cephalexin and other cephalosporins from 7-aminocephem compounds and organic acid esters. Among them, KY 7844 was one of the most promising organisms for enzymatic synthesis of cephalosporins. This organism had the ability to catalyze N-acylation of 7-aminocephem compound not only with α-amino acid ester, but also with such acid esters as 1-(1-H)-tetrazolylacetate methylester which has no α-amino group.

Search for Microorganisms Producing Cephalosporin Acylase and Enzymatic Synthesis of Cephalosporins.
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