Characterization of L-asparaginase from Streptomyces koyangensis SK4 with acrylamide-minimizing potential in potato chips

Abstract

Microbial L-asparaginase is well known for its application in food industries to reduce acrylamide content in fried starchy food. L-asparaginase produced by Arctic actinomycetes Streptomyces koyangensis SK4 was purified and studied for biochemical characterization. The L-asparaginase was purified with a yield of 15.49% and final specific activity of 179.77 IU/mg of protein. The enzyme exhibited a molecular weight of 43 kDa. The optimum pH and temperature for maximum activity of the purified enzyme were 8.5 °C and 40 °C, respectively. The enzyme expressed maximum activity at an incubation period of 30 min and a substrate concentration of 0.06 M. The enzyme has a low Km value of 0.041 M and excellent substrate specificity toward L-asparagine. The enzyme activity was inhibited by metal ions Ba²⁺ and Hg²⁺, while Mn²⁺ and Mg²⁺ enhanced the activity. The study evaluated the acrylamide reduction potential of L-asparaginase from Streptomyces koyangensis SK4 in potato chips. The blanching plus L-asparaginase treatment of potato slices resulted in a 50% reduction in acrylamide content. The study illustrated an effective acrylamide reduction strategy in potato chips using L-asparaginase from a psychrophilic actinomycete. Besides the acrylamide reduction potential, L-asparaginase from Streptomyces koyangensis SK4 also did not exhibit any glutaminase or urease activity which is an outstanding feature of L-asparaginase to be used as a chemotherapeutic agent.

Keywords: Acrylamide reduction; Arctic actinomycetes; Characterization; L-asparaginase; Purification.