School of Marine Sciences and Fisheries, Jiangsu Ocean University, Cangwu Road, Lianyungang, Jiangsu, People's Republic of China.
Curr Microbiol. 2023 Jul 19;80(9):292. doi: 10.1007/s00284-023-03406-w.
Arginase has shown promising potential in treating cancers by arginine deprivation therapy; however, low enzymatic activity and stability of arginase are impeding its development. This study was aimed to improve the enzymological properties of a marine bacterial arginase by carboxymethyl chitosan (CMCS) conjugation. An arginase producing marine bacterium Priestia megaterium strain P6 was isolated and identified. The novel arginase PMA from the strain was heterologously expressed, purified, and then conjugated to CMCS by ionic gelation with calcium chloride as the crosslinking agent. Enzymological properties of both PMA and CMCS-PMA conjugate were determined. The optimum temperature for PMA and CMCS-PMA at pH 7 were 60 °C and 55 °C, respectively. The optimum pH for PMA and CMCS-PMA at 37 °C were pH 10 and 9, respectively. CMCS-PMA showed higher thermostability than PMA over 55-70 °C and higher pH stability over pH 4-11 with the highest pH stability at pH 7. At 37 °C and pH of 7, i.e., around the human blood temperature and pH, CMCS-PMA was higher than the free PMA in enzymatic activity and stability by 24% and 21%, respectively. CMCS conjugation not only changed the optimum temperature, optimum pH, and enzymatic activity of PMA, but also improved its pH stability and temperature stability, and thus made it more favorable for medical application.
精氨酸酶通过精氨酸剥夺疗法显示出治疗癌症的巨大潜力；然而，其酶活性低和稳定性差限制了它的发展。本研究旨在通过羧甲基壳聚糖（CMCS）缀合来改善海洋细菌精氨酸酶的酶学性质。分离并鉴定了一株产精氨酸的海洋细菌 Priestia megaterium 菌株 P6。该菌株的新型精氨酸酶 PMA 经异源表达、纯化，然后用氯化钙作为交联剂通过离子凝胶法与 CMCS 缀合。测定了 PMA 和 CMCS-PMA 缀合物的酶学性质。在 pH 7 下，PMA 和 CMCS-PMA 的最适温度分别为 60°C 和 55°C。在 37°C 下，PMA 和 CMCS-PMA 的最适 pH 分别为 pH 10 和 pH 9。与 PMA 相比，CMCS-PMA 在 55-70°C 之间具有更高的热稳定性，在 pH4-11 之间具有更高的 pH 稳定性，在 pH7 时具有最高的 pH 稳定性。在 37°C 和 pH 7 下，即接近人体血液温度和 pH 值时，CMCS-PMA 的酶活性和稳定性比游离 PMA 分别高 24%和 21%。CMCS 缀合不仅改变了 PMA 的最适温度、最适 pH 和酶活性，而且提高了其 pH 稳定性和热稳定性，使其更有利于医学应用。
