Nozaki Y
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
Arch Biochem Biophys. 1990 Mar;277(2):324-33. doi: 10.1016/0003-9861(90)90587-o.
Second derivative spectrophotometry has been useful for the determination of aromatic amino acids. However, published methods produce erroneous results, because those methods measure second derivative values by the vertical distance between peak and trough which is subject to variation according to the aromatic amino acid composition of proteins. This paper presents a method of second derivative spectrophotometry which measures second derivative absorbance values by means of the vertical distance from baseline to the derivative curve at a wavelength specifically assigned to each aromatic amino acid, and makes corrections for the interference from other amino acids at the same wavelength. The Appendix describes a computational method for obtaining absolute values of second derivative absorbances directly from normal absorbance values without using the spectrophotometer's derivative mode, because most commercial instruments produce completely arbitrary second derivative values which make comparison of data obtained on two different instruments impossible.
二阶导数分光光度法已被用于芳香族氨基酸的测定。然而，已发表的方法会产生错误结果，因为那些方法是通过峰与谷之间的垂直距离来测量二阶导数值的，而该距离会因蛋白质中芳香族氨基酸的组成不同而变化。本文提出了一种二阶导数分光光度法，该方法通过在专门为每种芳香族氨基酸指定的波长下，从基线到导数曲线的垂直距离来测量二阶导数吸光度值，并对同一波长下其他氨基酸的干扰进行校正。附录描述了一种计算方法，可直接从正常吸光度值获得二阶导数吸光度的绝对值，而无需使用分光光度计的导数模式，因为大多数商用仪器产生的二阶导数值完全是任意的，这使得在两台不同仪器上获得的数据无法进行比较。
