叶酸与某些芳香族氨基酸相互作用的荧光光谱研究及分析应用

Fluorescence Spectroscopy Study on the Interaction Between Folic Acid and Some Aromatic a Mino Acids and Its Analytical Application

在pH 5.0的缓冲溶液中,叶酸与酪氨酸、色氨酸和苯丙氨酸3种芳香族氨基酸反应,使得上述芳香族氨基酸的荧光发生猝灭,最大猝灭波长分别位于304 nm(酪氨酸体系),353 nm(色氨酸体系),284 nm(苯丙氨酸体系),芳香族氨基酸的荧光猝灭值在一定范围内与叶酸浓度成正比.由此,建立荧光猝灭法测定叶酸的新方法,该方法的线性范围和检出限分别为:1.0×10-5-1.0×10-2g/L,5.2×10-6g/L(酪氨酸体系);1.0×10-5-1.5×10-2g/L,5.6×10-6g/L(色氨酸体系);5.0×10-6-8.0×10-3g/L,2.9×10-6g/L(苯丙氨酸体系).该方法已应用于实际样品的测定,并对荧光猝灭的机理进行讨论.

In pH 5.0 buffer medium, the folic acid reacted with some aromatic amino acids such as tryptophan, tyrosine and phenylalanine, which led to fluorescence quenching of above amino acids, and the maximum quenching wavelengths were 304 nm（FA -Tyr）, 353 nm（FA -Trp）, 284 nm（FA -Phe） respectively. Fluorescence quenching value was proportional to the concentration of folic acid in a certain range. A new method for deter minating folic acid by fluorescence quenching method was developed. The linear range of folic acid were 1.0 ×10-5 - 1.0 ×10-2 g/L for tyrosine system, 1.0 ×10-5 - 1.5 ×10-2 g/L for tryptophan system and 5.0 ×10-6 - 8. 0 ×10-3 g/L for phenylalanine system, respectively. The detection limit were 5. 2 ×10-6 g/L for tyrosine system, 5. 6 ×10-6 g/L for tryptophan system and 2. 9 ×10-6 g/L for phenylalanine system, respectively. This method has been applied to the deter ruination of the actual sample, and the mechanism of related reaction has also been discussed.