Abstract

The activity of novel uncharacterized extremophilic L-asparaginases from the psychrophilic fungi Sclerotinia borealis, the thermoacidophilic crenarchea Acidilobus saccharovorans, and the thermophilic bacteria Melioribacter roseus were studied. Active enzymes were produced via the expression of the native L-asparaginase gene from M. roseus (MrA) and synthetic genes encoding fungal S. borealis (SbA) and archeal A. saccharovorans (AsA) L-asparaginases after codon optimization in Escherichia coli cells. In the study, the maximum specific activity at different temperatures and pH was observed for MrA. The activity of MrA crude extract was highest at 75°С and a pH of 9.0. Metal ions (1 mM) differed in their effects on enzyme activity. Сu²⁺ and Zn²⁺ ions completely abolished enzyme activity. Changes in the specific activity of MrA crude extract in the presence of Fe³⁺, Ni²⁺, Ca²⁺, and Mg²⁺ varied within 5–28%. Our findings show that L-asparaginase of M. roseus may be a promising object for the further study of enzymatic properties and biotechnological applications.

中文翻译：

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极端微生物新型重组 L-天冬酰胺酶的酶活性比较

摘要

研究了来自嗜冷真菌Sclerotinia borealis、嗜热 crenarchea Acidilobus saccharovorans和嗜热细菌Melioribacter roseus的新型未表征的嗜极 L-天冬酰胺酶的活性。活性酶经由天然L-天冬酰胺基因的从表达产生M.长春花（MRA）和编码真菌合成基因S. 北极光（SBA）和古细菌A. saccharovorans（ASA）L-天冬酰胺酶后的密码子优化在大肠杆菌细胞。在研究中，观察到了 MrA 在不同温度和 pH 值下的最大比活性。MrA 粗提物的活性在 75°С 和 pH 值为 9.0 时最高。金属离子 (1 mM) 对酶活性的影响不同。Сu ²⁺和Zn ²⁺离子完全消除酶活性。在 Fe ³⁺、Ni ²⁺、Ca ²⁺和 Mg ²⁺存在下，MrA 粗提物的比活性变化在 5-28% 之间。我们的研究结果表明，玫瑰花的L-天冬酰胺酶可能是进一步研究酶学特性和生物技术应用的有希望的对象。