核酸、蛋白质的电荷数随pH的变化规律

从理论上推导出核酸、蛋白质的正电荷数随pH的变化关系式:Y=∑(i=1-3)H^+]~n~i/(H^+]+K~b~i),负电荷数随pH的变化关系式:X=∑(i=1-5)K~a~im~i/(H^+]+k~a~i)、净电荷数随pH变化关系式以及等电点计算关系式,并从关系式中导出核苷酸、碱基、中性氨基酸、酸性氨基酸、碱性氨基酸的等电点关系式,表明理论推导是正确、可靠的。用表面活性剂沉淀肌酸激酶、不同pH的溶菌酶电泳方法验证了计算结果的可靠性。同时,计算了人DNA、蚕DNA、β-乳球蛋白带电荷数随pH的变化规律,并估计了计算误差。

A study of the number of charges of nucleic acid and protein

In this study, the relation between the number of positive ( Y) or negative (X} charges of nucleic acid and the pH is derivedas Y = and X = respectively. The two relation are also applica- ble to the proteins. The pI formula of nucleotide, various amino acids and bases can be derived from the relations. This shows thet the relations are right and reliable. The net charges of Creatin Kinase at various pH calculated from the relations are confirmed by pretipitation of protein with surfactarnt, and electrophoresis. The variation of the number of charges of human DNA, silkworm DNA and B- lactoglobulia with pH is calculated.