title: Penicillin acylase-catalyzed synthesis of beta-lactam antibiotics in highly condensed aqueous systems: beneficial impact of kinetic substrate supersaturation.
abstract: Advantages of performing penicillin acylase-catalyzed synthesis of new penicillins and cephalosporins by enzymatic acyl transfer to the beta-lactam antibiotic nuclei in the supersaturated solutions of substrates have been demonstrated. It has been shown that the effective nucleophile reactivity of 6-aminopenicillanic (6-APA) and 7-aminodesacetoxycephalosporanic (7-ADCA) acids in their supersaturated solutions continue to grow proportionally to the nucleophile concentration. As a result, synthesis/hydrolysis ratio in the enzymatic synthesis can be significantly (up to three times) increased due to the nucleophile supersaturation. In the antibiotic nuclei conversion to the target antibiotic the remarkable improvement (up to 14%) has been gained. Methods of obtaining relatively stable supersaturated solutions of 6-APA, 7-ADCA, and D-p-hydroxyphenylglycine amide (D-HPGA) have been developed and syntheses of ampicillin, amoxicillin, and cephalexin starting from the supersaturated homogeneous solutions of substrates were performed. Higher synthetic efficiency and increased productivity of these reactions compared to the heterogeneous "aqueous solution-precipitate" systems were observed. The suggested approach seems to be an effective solution for the aqueous synthesis of the most widely requested beta-lactam antibiotics (i.e., amoxicillin, cephalexin, cephadroxil, cephaclor, etc.).
authors.affiliation: Belozersky Institute of Physicochemical Biology and Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119992, Moscow,Russia.
authors.forename: Maxim I
authors.initials: MI
authors.lastname: Youshko
authors.forename: Harold M
authors.initials: HM
authors.lastname: Moody
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Bukhanov
authors.forename: Wilhelmus H J
authors.initials: WH
authors.lastname: Boosten
authors.forename: Vytas K
authors.initials: VK
authors.lastname: Svedas
mesh_terms: D000658:Amoxicillin / Q000138:chemical synthesis; D000667:Ampicillin / Q000138:chemical synthesis; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis*; D002384:Catalysis; D002506:Cephalexin / Q000138:chemical synthesis; D002511:Cephalosporins / Q000737:chemistry; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D010399:Penicillin Amidase / Q000737:chemistry*; D012996:Solutions; D013379:Substrate Specificity; D014867:Water / Q000737:chemistry*; D047090:beta-Lactams / Q000138:chemical synthesis*
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D012996:Solutions; D047090:beta-Lactams; D014867:Water; D000667:Ampicillin; D000658:Amoxicillin; D010397:Penicillanic Acid; C014320:7-aminodesacetoxycephalosporanic acid; D010399:Penicillin Amidase; D002506:Cephalexin; C004408:aminopenicillanic acid