Enzymatic hydrolysis of beta-lactam antibiotics at low pH in a two-phase 'aqueous solution-water-immiscible organic solvent' system

摘要

The application of the two-phase "aqueous solution-water-immiscible organic solvent" system is suggested not for effective biocatalytic synthesis, but for hydrolytic purposes. Enzymatic hydrolysis of benzylpenicillin and N-phenylacetamidodesacetoxycephalosporanic acid to corresponding antibiotic nuclei 6-aminopenicillanic and 7-aminodesacetoxycephalosporanic acid in a two -phase water-butylacetate system at pH 3-4 is proposed as an alternative to the biocatalytic hydrolysis in an alkanine medium. An experimental study has been performed and a model has been developed, which describes the influence of pH, phase volume ratio, thermodynamic constants, and initial antibiotic concentration on the effectiveness of their hydrolysis in a two-phase "aqueous solution - water-immiscible organic solvent" system. The thremodynamic evaluation of penicillin G and 7-phenylacetamidodesacetoxycephalosoranic acid hydrolysis at low pH in a two-phase aqueous solution-water-immiscible organic solvent system has demonstrated high practical potential. The suggested approach allows for the exclusionn of several technological steps during the transformation of natural beta-lactam antibiotics to their semi-synthetic analogues: alkaline extraction of the biosynthetic antibiotic from butylacetate followed by its enzymatic hydrolysis at pH 7.5-8.0 and further acidification of the reaction mixture, which results in the precipitation of the antibiotic nucleus. Experimental observations also revealed a specific feature of this process: the kinetic supersaturation of the antibiotic nucleus shows down the attainment of the equilibrium, which should be taken into account when further developing this approach.