Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Centro de Investigaciones y Transferencia de Entre Ríos (CITER), Monseñor Tavella 1450 (E3202 BCJ), Concordia, Entre Ríos, Argentina.
Facultad de Ciencias de la Alimentación, Universidad Nacional de Entre Ríos, Monseñor Tavella 1450 (E3202 BCJ), Concordia, Entre Ríos, Argentina.
Appl Biochem Biotechnol. 2021 Oct;193(10):3121-3138. doi: 10.1007/s12010-021-03596-8. Epub 2021 Jun 3.
L-glutaminases are enzymes that catalyze the hydrolysis of L-glutamine, producing L-glutamate and ammonium, and they have promising applications in pharmaceutical and food industries. Several investigations have focused on thermo-tolerant L-glutaminases; however, studies on cold-adapted L-glutaminases have not been reported. These enzymes could be useful in the food industry because they display high catalytic activity at low and room temperatures, a valuable feature in processes aimed to save energy. Besides, they can be easily inactivated by warming and are suitable to prevent decomposition of thermo-labile compounds. The objectives of this work were to characterize the L-glutaminase from the Antarctic bacterium Bizionia argentinensis and analyze its capability as flavor enhancer of protein hydrolysates. The enzyme was heterologously expressed and purified from Escherichia coli, obtaining optimum and homogeneous yields. Kinetic parameters K and V were located at the lower and upper range of values reported for L-glutaminases, suggesting high catalytic efficiency. Optimum temperature was 25 °C, and the enzyme conserved around 90% of maximum activity at 0 °C and in presence of 15% (v/v) ethanol and methanol. In saline conditions, the enzyme conserved around 80% of maximum activity in 3 M NaCl. Analysis of structural model suggested cold-adaptation features such as low Arg/(Arg+Lys) ratio and fewer intramolecular interactions than mesophilic and thermo-tolerant L-glutaminases. This work provides a novel cold-adapted L-glutaminase with promising features in the food industry.
L-谷氨酰胺酶是一种能够催化 L-谷氨酰胺水解的酶，生成 L-谷氨酸和氨，在医药和食品工业中有广泛的应用。有许多研究都集中在耐热 L-谷氨酰胺酶上；然而，对于耐冷 L-谷氨酰胺酶的研究尚未报道。这些酶在食品工业中可能很有用，因为它们在低温和室温下具有高催化活性，这是在旨在节约能源的过程中很有价值的特性。此外，它们可以通过加热轻易失活，并且适合用于防止热敏化合物的分解。本工作的目的是对来自南极细菌 Bizionia argentinensis 的 L-谷氨酰胺酶进行表征，并分析其作为蛋白质水解物风味增强剂的能力。该酶通过大肠杆菌异源表达和纯化获得，得到了最佳和均一的产量。动力学参数 K 和 V 位于报道的 L-谷氨酰胺酶的较低和较高值范围内，表明具有较高的催化效率。最适温度为 25°C，该酶在 0°C 和 15%（v/v）乙醇和甲醇存在下保持约 90%的最大活性。在盐条件下，该酶在 3 M NaCl 中保持约 80%的最大活性。结构模型分析表明，该酶具有低温适应的特征，如低 Arg/(Arg+Lys) 比和比嗜温和耐热 L-谷氨酰胺酶更少的分子内相互作用。这项工作提供了一种具有食品工业应用前景的新型耐冷 L-谷氨酰胺酶。
