Kumar Acharya B Vishu, Gowda Lalitha R, Tharanathan Rudrapatnam N
Department of Biochemistry and Nutrition, Central Food Technological Research Institute, Mysore, India.
Eur J Biochem. 2004 Feb;271(4):713-23. doi: 10.1111/j.1432-1033.2003.03975.x.
Pronase (type XXV serine protease from Streptomyces griseus) efficiently depolymerizes chitosan, a linear beta-->1,4-linked polysaccharide of 2-amino-deoxyglucose and 2-amino-2-N-acetylamino-D-glucose, to low-molecular weight chitosans (LMWC), chito-oligomers (degree of polymerization, 2-6) and monomer. The maximum depolymerization occurred at pH 3.5 and 37 degrees C, and the reaction obeyed Michaelis-Menten kinetics with a Km of 5.21 mg.mL(-1) and Vmax of 138.55 nmoles.min(-1).mg(-1). The molecular mass of the major product, LMWC, varied between 9.0 +/- 0.5 kDa depending on the reaction time. Scanning electron microscopy of LMWC showed an approximately eightfold decrease in particle size and characterization by infrared spectroscopy, circular dichroism, X-ray diffractometry and 13C-NMR revealed them to possess a lower degree of acetylation, hydration and crystallinity compared to chitosan. Chitosanolysis by pronase is an alternative and inexpensive method to produce a variety of chitosan degradation products that have wide and varied biofunctionalities.
链霉蛋白酶（来自灰色链霉菌的XXV型丝氨酸蛋白酶）能有效地将壳聚糖（一种由2-氨基脱氧葡萄糖和2-氨基-2-N-乙酰氨基-D-葡萄糖组成的线性β-1,4-连接的多糖）解聚为低分子量壳聚糖（LMWC）、壳寡糖（聚合度为2-6）和单体。最大解聚发生在pH 3.5和37℃，反应符合米氏动力学，Km为5.21mg·mL⁻¹，Vmax为138.55nmol·min⁻¹·mg⁻¹。主要产物LMWC的分子量根据反应时间在9.0±0.5 kDa之间变化。LMWC的扫描电子显微镜显示颗粒尺寸大约减小了八倍，通过红外光谱、圆二色性、X射线衍射和¹³C-NMR表征发现，与壳聚糖相比，它们的乙酰化程度、水合程度和结晶度较低。链霉蛋白酶进行的壳聚糖分解是一种替代且廉价的方法，可生产具有广泛多样生物功能的各种壳聚糖降解产物。
