CYTOFLUOROMETRIC DETERMINATION OF LYSINE WITH DANSYLCHLORIDE

Dansylchloride (l-dimethylamino-naphthalene-5-sulfochloride) may be used for cytofluorometric determination of lysine. By means of model experiments on protein smears it is shown that the reaction must be carried out in ethanol if it is to be specific for amino groups. The fluorescence given by isolated rat liver nuclei treated with dansylchloride corresponds to the three classes of 2n, 4n and 8n nuclei. The dansylfluorescence of several kinds of sperms is proportional to their lysine content. In rat liver nuclei, 95% of the lysine is dansylated and the lysine content may be determined in absolute values by comparison with polylysine. In spermatozoa only 50% of the lysine reacts.