Enzymatic synthesis of Cephalexin in recyclable aqueous two-phase systems composed by two pH responsive polymers

• A recyclable ATPS composed by two pH-response copolymers was prepared.
• Substrates K7-ADCA and KPGME are biased in bottom phase, and product KCephalexin is biased in top phase.
• Synthesis of Cephalexin in ATPS has been conducted with 98.2% yield.
• Ratio of acyl donor to nucleophile decreased from 3 to 2.

The synthesis of Cephalexin in novel recyclable aqueous two-phase systems was studied, using immobilized penicillin acylase as biocatalyst, 7-amino-3-desacetoxy cephalosporanic acid (7-ADCA) as nucleophile and phenyl glycine methyl ester (PGME) as acyl donor. The aqueous two-phase system (ATPS) was composed by two pH-response copolymers PADBA and PMDB, which could be recycled efficiently. In the ATPS, high partition coefficient (2.57) for Cephalexin and low partition coefficient (0.21) for 7-ADCA were obtained. Then the synthesis of Cephalexin in ATPS and conventional one-phase system was compared. Higher Cephalexin yield was obtained in ATPS. In addition, synthesis in ATPS was improved at higher substrates concentrations, obtaining yield of 98.2% with 50 mM 7-ADCA and 150 mM PGME at pH 5.8, 20 °C. Even reducing acyl donor to nucleophile ratio to 2, the yield can still above 90%. PADBA/PMDB recycling aqueous two-phase system is suitable for synthesis of Cephalexin.