乳清中乳碱性蛋白的分离与纯化

利用离子交换和葡聚糖凝胶层析等技术从制作干酪的副产物乳清中提取乳碱性蛋白。分别以洗脱速度、洗脱温度、洗脱液浓度为因素，进行L9(34)正交试验，最终得出各因素对离子交换树脂提取效果的影响主次顺序依次为洗脱速度＞洗脱温度＞洗脱液浓度；采用D072 强酸性阳离子交换树脂提取乳碱性蛋白的最佳洗脱条件为洗脱速度2.50mL/min、洗脱温度40℃、洗脱液浓度0.04mol/L。在该条件下的乳碱性蛋白提取率为7.55%。在制得的粗MBP 的基础上，利用Sephadex G-100 型葡聚糖凝胶，蛋白分离范围4000～150000D，对其进行纯化，测得最终纯度为83.55%。

Isolation and Purification of Milk Basic Protein from Cheese Whey

Milk basic protein (MBP) is one part of whey protein. It has been reported to suppress osteoclast-mediated bone resorption in vitro. In the present study, MBP was extracted from byproduct whey of Mozzaralla cheese making by ion exchange chromatography and the resultant crude extract was purified by polydextran gel chromatography. Four strongly acidic cation exchange resins were used to adsorb MBP, and D072 type resin was selected due to the highest adsorption capacity. Single factor and orthogonal array design methods were employed to optimize conditions (desorption flow rate, temperature and concentration of desorption solvent, phosphate buffer) for the desorption of MBP from D072 type resin. The results showed that desorption flow rate had the most significant effect on MBP desorption, followed by temperature and desorption solvent concentration. Their optimum values were found to be: desorption flow rate 2.50 mL/min, temperature 40 ℃ and desorption solvent concentration 0.04 mol/L. Under these conditions, a MBP yield of 7.55% was obtained. After the purification with Sephadex G-100 with 4000 － 150000 D separation scope, a MBP product with 83.55% purity was obtained.