Asparaginase with Combined Mutations: Optimized Biochemistry and Lowered Allergic Risk

Abstract

Biotechnology and biomedical advances have driven the development of novel biopharmaceuticals to meet growing clinical demands. Among approved biologics, native Escherichia coli asparaginase has been under continuous optimization to improve thermostability, half-life, resistance to human proteases, and reduce adverse effects, particularly allergenicity. Here, we engineered an antileukemic biobetter by combining the substitutions P40S/S206C─previously identified by our group as less immunogenic and with extended bloodstream activity in mice─with N24S, reported to enhance in vitro stability. The purified triple mutant enzyme was biochemically characterized, and its cytotoxicity against leukemic cell lines and antigenic properties in Balb/c SPF mice were evaluated. TM displayed robust asparaginase activity, a >3-fold reduction in KMfor asparagine, superior thermostability, enhanced proteolytic resistance, and a lower in silico immunogenicity score compared to wild-type. In vivo, compared to wild-type, TM showed no apparent toxicity, a lower decrease in platelet counts, reduced induction of antiasparaginase IgE antibodies, and a preserved pharmacokinetic profile. In conclusion, combined mutations conferred substantial biochemical and immunological improvements, supporting the strategy of targeted amino acid substitutions to advance next-generation asparaginase biopharmaceuticals.