| Popis: |
Penicillin acylase-catalyzed ampicillin synthesis via acyl group transfer in aqueous solution is highly dependent on the initial substrate concentration. The solubility of one substrate, 6-aminopenicillanic acid (6-APA), can be advantageously enhanced by the presence of acyl donor, the second substrate. Furthermore, a comparison of enzymatic synthesis in homogeneous solution with synthesis in a heterogeneous system having partially undissolved reactants, reveals major advantages for the latter approach. In this “aqueous solution–precipitate” system, accumulation of both products, ampicillin and d -(−)-phenylglycine, proceeds through the formation of their supersaturated solutions. Subsequent precipitation of the product ampicillin positively influences the efficiency of the biocatalytic process. As a result, ampicillin synthesis proceeds in 93% conversion on 6-APA and in 60% conversion on d -(−)-phenylglycine methyl ester. |
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