酶法改性对蛋白质结构性质的影响及与酶特异性的关系

采用分子生物物理学原理探讨了蛋白质的平均分子量、水化面积、极性、憎水性、柔性及电荷分布与酶作用的关系.研究表明:改性蛋白质的平均分子量与水解度成反比例关系;水化面积随水解度的增加成对数关系增大;极性与平均分子量成反比例关系;柔性与平均分子量成负指数函数关系;净电荷数在pH、温度和蛋白质浓度一定的条件下,随水解度的增加成正比例关系增大.改性蛋白质的憎水性由两部分构成,分别为肽键断裂引起憎水性的变化和构象变化引起的变化.其中肽键断裂引起憎水性变化与水解度成正比关系.总之,改性蛋白质的结构性质变化与酶作用之间存在明显的定量关系,而且结构性质的变化还与酶特异性有关.

EFFECT OF ENZYMATICAL MODIFICATIONON THE STRUCTURAL PROPERTIES OF PROTEINS AND ITS RELATIONSHIP WITH ENZYME SPECIFI- CITY

This paper studied the effect of enzyme on the structural properties of EMP (Enzymatcal Modified proteins) . On the base of preceding works in this field the author inve stigated the relationships between structural properties (the average molecular weight (AMW) , water accessible area, polarity, hydrophobicity, flexibility and electric charge distribution) of EMP and the degree of enzymatical modification with the principles of biophysics. Some results folloeing have been obtained. The AMW of EMP is inversely proportional to the DH (degree of hydrolysis) . The water accessible area of EMP is logarithmic function of the DH. The polarity of EMP is inversely proportional to AMW. The flexibility of EMP is a negative exponential function of AMW. The net charge of EMP with certain PH, temperature and protein concentration is proportional to the DH. Changes in hydrophobicity of EMP is composed of breaking of peptide bond that the hydrophobicity change resulted in is proportional to the DH EMP and conformation changes. In conclusion, there is a quantitative relationship between structural properties and enzymatical modification, which is related to the enzyme specificity.