DERIVATIVE SPECTROPHOTOMETRIC METHOD FOR THE ANALYSIS OF TYROSINE IN UNHYDROLYZED PROTEIN, FOOD, AND FEEDSTUFF SAMPLES

A rapid and simple procedure for the analysis of tyrosine in proteinaceous materials has been developed. Sample is homogenized with sodium hydroxide solution, and the homogenate is centrifuged. Tyrosine is directly quantified in sample extract on the basis of the characteristic fourth derivative trough appearing at around 257.2 nm. Prior hydrolysis or additional cleanup of the extract is not required. The method can be directly applied to a large variety of samples including proteins, foods, and feedstuffs. When a number of pure proteins were analyzed by the method, the values of tyrosine residues found within proteins coincided quite well with sequence data of the literature.