Vishu Kumar A B, Varadaraj M C, Lalitha R G, Tharanathan R N
Department of Biochemistry and Nutrition, Central Food Technological Research Institute, Mysore-570 013, India.
Biochim Biophys Acta. 2004 Jan 22;1670(2):137-46. doi: 10.1016/j.bbagen.2003.11.004.
Low molecular weight chitosans (LMWC) of different molecular weight (4.1-5.6 kDa) were obtained by the depolymerization of chitosan using papain (from Carica papaya latex, EC. 3.4.22.2) at optimum conditions of pH 3.5 and 37 degrees C for 1-5 h. Scanning electron microscopy (SEM) showed approximately 15-fold decrease in the particle size after depolymerization. Decrease in the molecular weight was associated with decrease in the degree of acetylation (DA) as evidenced by circular dichroism (CD), FT-IR and solid-state CP-MAS 13C-NMR data. X-ray diffraction pattern revealed slight decrease in the crystallinity index (CrI) whereas the 13C-NMR data showed molecular inhomogeneity. LMWC showed lytic effect towards Bacillus cereus and Escherichia coli more efficiently than native chitosan. The growth inhibitory effect was maximal towards B. cereus, with minimum inhibitory concentration (MIC) of 0.01% (w/v).
通过在pH 3.5和37℃的最佳条件下，使用木瓜蛋白酶（来自番木瓜乳胶，EC. 3.4.22.2）对壳聚糖进行解聚1 - 5小时，获得了不同分子量（4.1 - 5.6 kDa）的低分子量壳聚糖（LMWC）。扫描电子显微镜（SEM）显示解聚后粒径大约减小了15倍。圆二色性（CD）、傅里叶变换红外光谱（FT - IR）和固态交叉极化魔角旋转13C - 核磁共振（CP - MAS 13C - NMR）数据表明，分子量的降低与乙酰化程度（DA）的降低有关。X射线衍射图谱显示结晶度指数（CrI）略有下降，而13C - NMR数据显示分子不均匀性。与天然壳聚糖相比，LMWC对蜡样芽孢杆菌和大肠杆菌表现出更有效的裂解作用。对蜡样芽孢杆菌的生长抑制作用最大，最低抑菌浓度（MIC）为0.01%（w/v）。
