用碱水解的方法测定蛋白质的消光系数

在蛋白质结构与功能的研究中，有时蛋白质溶液的浓度是一个重要的参数.紫外吸收法是测定蛋白质溶液浓度最为常用的方法，而已知蛋白质的消光系数是用紫外吸收法准确测定蛋白质溶液浓度的前提条件.在0.1 mol/L NaOH溶液中，蛋白质发生碱性水解，因而蛋白质溶液可以看作是色氨酸和酪氨酸的二元体系.以此为依据，给出了用碱水解的方法测定蛋白质消光系数的方法.这一方法操作步骤简便易行，蛋白质消光系数的计算公式简单明了.用这一碱水解的方法分别测定了几种氨基酸组成不同的蛋白质的消光系数，与文献数据对照，得到了令人满意的结果，测定误差均小于±5％.

Determination of Protein Extinction Coefficients by Alkaline Hydrolysis

Quantitative study of protein requires accurate determination of protein concentration. Yet without a reliable value of protein extinction coefficient, it is difficult or impossible to determine protein concentration by the usual UV spectroscopic means. On the basis of the extinction coefficients of tyrosine and tryptophan in 0.1 mol/L NaOH solution, a method was introduced for determining accurate extinction coefficients for proteins at 280 nm by protein alkaline hydrolysis. Meanwhile, this method is calibrated against several proteins whose extinction coefficients are known from references. The results show that the extinction coefficients of these proteins determined by the alkaline hydrolysis method are accurate.