[Determination of tyrosine and tryptophan in proteins by the absorption spectra of derivatives].

The contents of tyrosine and tryptophan were determined by the method based on the first derivatives of the proteins absorption spectra within the alkali pH. The advantages of the method are as follows: a much better resolution of tyrosine and tryptophan spectral maxima located at 293 and 307 nm, respectively, which allows the precision of their assay to be increased, especially in case of a small amount of one amino acid and relative abundance of the other and high turbidity of the preparations; the account of the cystine absorption is not necessary; possibility to study proteins containing the chromophore prosthetic groups.