College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China.
Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, 43500 Semenyih, Selangor Darul Ehsan, Malaysia.
J Biosci Bioeng. 2020 Jun;129(6):672-678. doi: 10.1016/j.jbiosc.2020.01.007. Epub 2020 Feb 20.
l-Asparaginases have the potential to inhibit the formation of acrylamide, a harmful toxin formed during high temperature processing of food. A novel bacterium which produces l-asparaginase was screened. Type I l-asparaginase gene from Acinetobacter soli was cloned and expressed in Escherichia coli. The recombinant l-asparaginase had an activity of 42.0 IU mL and showed no activity toward l-glutamine and d-asparagine. The recombinant l-asparaginase exhibited maximum catalytic activity at pH 8.0 and 40°C. The enzyme was stable in the pH ranging from 6.0 to 9.0. The activity of the recombinant enzyme was substantially enhanced by Ba, dithiothreitol, and β-mercaptoethanol. The K and V values of the l-asparaginase for the l-asparagine were 3.22 mmol L and 1.55 IU μg, respectively. Moreover, the recombinant l-asparaginase had the ability to mitigate acrylamide formation in potato chips. Compared with the untreated group, the content of acrylamide in samples treated with the enzyme was effectively decreased by 55.9%. These results indicate that the novel type I l-asparaginase has the potential for application in the food processing industry.
天冬酰胺酶有可能抑制丙烯酰胺的形成，丙烯酰胺是食物在高温加工过程中形成的一种有害毒素。筛选出一种能产生天冬酰胺酶的新型细菌。从土壤固氮菌中克隆并在大肠杆菌中表达了 I 型天冬酰胺酶基因。重组天冬酰胺酶的活性为 42.0 IU mL，对 l-谷氨酰胺和 d-天冬酰胺没有活性。重组天冬酰胺酶在 pH8.0 和 40°C 时表现出最大的催化活性。该酶在 pH6.0 到 9.0 的范围内稳定。Ba、二硫苏糖醇和β-巯基乙醇可显著提高重组酶的活性。该天冬酰胺酶对天冬酰胺的 K 和 V 值分别为 3.22 mmol L 和 1.55 IU μg。此外，重组天冬酰胺酶具有减轻薯片丙烯酰胺形成的能力。与未处理组相比，用酶处理的样品中的丙烯酰胺含量有效降低了 55.9%。这些结果表明，新型 I 型天冬酰胺酶有可能应用于食品加工业。
