Bidochka M J, Tong K I, Khachatourians G G
Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon, Canada.
Can J Microbiol. 1993 Jan;39(1):40-5. doi: 10.1139/m93-006.
Beauveria bassiana grown in a liquid medium containing N-acetyl-D-glucosamine and colloidal chitin produced two distinct N-acetyl-D-glucosaminidases, NAGase 1 and NAGase 2. NAGase 1 had a molecular weight of 97,000 and NAGase 2 was comprised of two subunits, of molecular weights 64,000 and 66,000. The optimal temperature and pH for NAGase 1 were 57 degrees C and pH 5 and for NAGase 2 they were 37 degrees C and pH 5. NAGase 1 was more thermostable than NAGase 2. The isolectric points of NAGase 1 and 2 were ca. pH 9.5 and 5.5, respectively. NAGase 1 and 2 were unaffected by a 10 mM concentration of chloride salts of the ions Ca2+, Mg2+, or Zn2+, by 10 mM EDTA, and by 0.25-1 mM of short chain fatty acids. Dithiothreitol caused some inactivation of NAGase 2 while stimulating activity of NAGase 1. NAGase 1 had a Km of 0.38 mM and a Kcat/Km of 3923.88 M-1.s-1.NAGase 2 had a Km of 2.095 mM and a Kcat/Km of 411.88 M-1.s-1 when p-nitrophenyl-beta-N-acetylglucosaminide was used as the substrate.
在含有N-乙酰-D-葡萄糖胺和胶体几丁质的液体培养基中生长的球孢白僵菌产生了两种不同的N-乙酰-D-葡萄糖苷酶，即NAGase 1和NAGase 2。NAGase 1的分子量为97,000，NAGase 2由分子量分别为64,000和66,000的两个亚基组成。NAGase 1的最适温度和pH分别为57℃和pH 5，NAGase 2的最适温度和pH分别为37℃和pH 5。NAGase 1比NAGase 2更耐热。NAGase 1和2的等电点分别约为pH 9.5和5.5。NAGase 1和2不受10 mM浓度的Ca2+、Mg2+或Zn2+离子的氯化物盐、10 mM乙二胺四乙酸（EDTA）以及0.25 - 1 mM短链脂肪酸的影响。二硫苏糖醇使NAGase 2发生一些失活，同时刺激NAGase 1的活性。当以对硝基苯基-β-N-乙酰氨基葡萄糖苷为底物时，NAGase 1的Km为0.38 mM，Kcat/Km为3923.88 M-1·s-1；NAGase 2的Km为2.095 mM，Kcat/Km为411.88 M-1·s-1。
