Preparation of casein
I. The purpose and requirements
1. Master to use the centrifuge;
2. Master prepared from milk casein in the principles and methods. II. The experimental principle
Casein is protein phosphorus, but also the heterogeneous mixture, rich in Tyr, Met, Gys, (Gys) 2, pI equal to 4.7 to 4.8, insoluble in ethanol. The experimental use when in the isoelectric point of the principle of minimum solubility, the milk's pH to 4.7, the casein will precipitate out. Sediment washed with ethanol to remove lipid impurities, you get pure casein
III. Equipment and reagents
1. Equipment
a. Centrifuges
b. Filtration system(Buchner funnel);
c. Constant temperature heating device
2. Reagent
a. pH4.7 acetic acid - sodium acetate buffer (0.2mol/L) 30ml
b. Milk 30ml
c.95% ethanol
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