A new fluorescent method with phenanthrenequinone for the histochemical demonstration of arginine residues in tissues.

Abstract

Phenanthrenequinone, in an alkaline ethanolic solution, is shown to be specific for the guanidino group of arginine in tissues. The fluorescence measured in chick erythrocyte nuclei is highly reproducible among areas on one slide and among different slides. Benzil and cyclohexanedione, two agents known to be specific for the guanidino group, prevent 85% of the fluorescence developed in the phenanthrenequinone reaction. Glyoxal blocks phenanthrenequinone reactivity only partially, while alkaline formaldehyde has little effect. The effects of fixation and postfixation of chick erythrocyte nuclei indicate that fluorescence is most intense after formalin fixation, and that conformational factors may prevent ethanolacetic acid-fixed nuclei from reacting completely. By means of protein precipitation and prolonged incubation in ethanol, it was shown that the fluorescent chromophore is strongly bound to phenanthrenequinone-reacted gelatin and to tissue sections. Excitation and emission spectra are presented for phenanthrenequinone-reacted arginine, gelatin and a tissue section.