Wolf P
Anal Biochem. 1983 Feb 15;129(1):145-55. doi: 10.1016/0003-2697(83)90062-3.
Waddell's method of estimating protein concentration by the difference between spectrophotometric absorptions (215-225 nm) has been reexamined. Over limited ranges of total protein, a linear relation was found for ten purified proteins; the narrowest range was between 5 and 25 micrograms/ml. Using published extinction coefficients at 280 nm for these ten proteins, protein concentration at 280 nm correlated closely with the 215 nm/225 nm difference measurements (mean difference of 2.6%). Waddell's method also accurately determined the total protein in a mixture of proteins with widely varying individual 280-nm extinction coefficients. Biuret estimates of total protein in plasma or serum gave poor correlation with measurements by Waddell's method. Within protein concentration limits, Waddell's method was linear, narrow, and more variable, both for individual proteins and for protein mixtures, than previously reported. Within these limits, the method is probably as accurate a measure of total protein as measurement by nitrogen analysis, with the advantage of being nondestructive.
已对沃德尔通过分光光度吸收差异（215 - 225纳米）估算蛋白质浓度的方法进行了重新审视。在总蛋白的有限范围内，发现十种纯化蛋白质呈线性关系；最窄范围是5至25微克/毫升。利用已发表的这十种蛋白质在280纳米处的消光系数，280纳米处的蛋白质浓度与215纳米/225纳米差异测量值密切相关（平均差异为2.6%）。沃德尔方法还准确测定了具有广泛不同的单个280纳米消光系数的蛋白质混合物中的总蛋白。血浆或血清中总蛋白的双缩脲估计值与沃德尔方法的测量结果相关性较差。在蛋白质浓度范围内，沃德尔方法对于单个蛋白质和蛋白质混合物而言，比之前报道的更具线性、范围更窄且变化更大。在这些范围内，该方法可能与通过氮分析测量总蛋白一样准确，且具有无损的优点。
