Goo Bon Geun, Park Jae Kweon
Department of Pharmaceutical Science, Gachon University, 191 Hambakmoeiro, Yeonsu-dong, Yeonsu-gu, InCheon 406-799, Republic of Korea.
Department of Life Science, College of Bionano, Gachon University, 191 Hambakmoeiro, Yeonsu-dong, Yeonsu-gu, InCheon 406-799, Republic of Korea.
J Biosci Bioeng. 2014 Jun;117(6):684-9. doi: 10.1016/j.jbiosc.2013.11.005. Epub 2013 Dec 9.
An alkalophilic extracellular chitosanase (ACTase) was characterized from the culture supernatant of Bacillus cereus GU-02. Kinetic properties of ACTase produced from B. cereus GU-02 after cultivation in anaerobic condition, alkaline medium (pH 10) at 37°C for 3 days were investigated. ACTase was found to be stable in alkaline pH range from 8 to 10. Interestingly, optimum pH and temperature were estimated to be 10 and 37°C, respectively, where ACTase showed chitosan degrading activity (87%), which was enhanced by 15% in the presence of calcium ions (8 mM). The ACTase produced from B. cereus GU-02 was partially purified from the culture supernatant, and its enzymatic activity was kinetically characterized. The Vmax and Km were estimated with a chitosan (degree of deacetylation, DD 92% as substrate) as 0.038 U/min/μg protein and 0.327 μM, respectively. A combination of the TLC and MALDI-TOF MS results showed that the chitosan oligosaccharides obtained from the hydrolysis of high molecular weight chitosan (HMWC) by ACTase of the B. cereus GU-2 comprise oligomers with degree of polymerization (DP) mainly from dimers to pentamers. High production of ACTase and chitooligosaccharides may be useful for various industrial and biological applications.
从蜡样芽孢杆菌GU-02的培养上清液中鉴定出一种嗜碱细胞外壳聚糖酶（ACTase）。研究了蜡样芽孢杆菌GU-02在37°C厌氧条件下的碱性培养基（pH 10）中培养3天后产生的ACTase的动力学特性。发现ACTase在pH 8至10的碱性范围内稳定。有趣的是，最佳pH和温度分别估计为10和37°C，此时ACTase表现出壳聚糖降解活性（87%），在存在钙离子（8 mM）的情况下，该活性提高了15%。从蜡样芽孢杆菌GU-02产生的ACTase从培养上清液中部分纯化，并对其酶活性进行了动力学表征。以脱乙酰度（DD 92%）的壳聚糖为底物，Vmax和Km分别估计为0.038 U/min/μg蛋白质和0.327 μM。TLC和MALDI-TOF MS结果相结合表明，蜡样芽孢杆菌GU-2的ACTase水解高分子量壳聚糖（HMWC）得到的壳寡糖主要由二聚体到五聚体的低聚物组成。ACTase和壳寡糖的高产率可能对各种工业和生物应用有用。
