A novel bacterial type II l-asparaginase and evaluation of its enzymatic acrylamide reduction in French fries

This study reports the identification of a novel bacterial type II l-asparaginase, abASNase2, from Aquabacterium sp. A7-Y. The enzyme contains 319 amino acids and shared 35% identity with Escherichia coli type II l-asparaginase (EcAII), a commercial enzyme trademarked Elspar® that is widely used for medical applications. abASNase2 had high specific activity (458.9 U/mg) toward l-asparagine, very low activity toward l-glutamine and d-glutamine and no activity toward d-asparagine. The optimal enzymatic activity conditions for abASNase2 were found to be 50 mM Tris-HCl buffer (pH 9.0) at 60 °C. It was very stable in the pH range of 7.0-11.0 and exhibited up to 80% relative activity after 2 h below 40 °C. The Km and kcat of abASNase2 were 1.8 × 10−3 M and 241.9 s−1, respectively. In addition, abASNase2's ability to remove acrylamide from fried potato strips was evaluated. Compared to untreated potato strips (acrylamide content: 0.823 ± 0.0457 mg/kg), 88.2% acrylamide was removed in the abASNase2-treated group (acrylamide content: 0.097 ± 0.0157 mg/kg). These results indicate that the novel l-asparaginase abASNase2 is a potential candidate for applications in the food processing industry.