HISTOCHEMICAL REACTIONS AT TISSUE ARGININE SITES WITH ALKALINE SOLUTIONS OF -NAPHTHOQUINONE-4-SODIUM SULFONATE AND OTHER o-QUINONES AND OXIDIZED o-DIPHENOLS A POSSIBLE MECHANISM OF THE SAKAGUCHI REACTION
Speculation on the possible role of an o-quinone in the traditional Sakaguchi arginine reaction led to the trial of sodium 1,2-naphthoquinone-4-sulfonate in Deitch's barium hydroxide solvent. An intense red reaction is produced in sperm heads, Paneth cell and eosinophil leukocyte granules, keratohyalin, trichohyalin, hair medulla and alkali-treated hair cortex; weaker reactions are produced in keratin, collagen, muscle and resting nuclei. Alkaline benzil, 1,2-cyclohexanedione and 9,10-phenanthrenequinone treatments prevent the reaction completely, glyoxal does partly and nitrous acid deamination has no effect; some acylations are partially effective and in part reversible; methylation attenuates, reversibly; aldehyde and SH blockades are ineffective. The reaction requires 6-10 min for full development; longer exposures do not increase the density. The extreme reaction pH range is from about 12.4 to about 13.6; the reaction is optimal at 13.2-13.4 (ca. 0.2-0.4 N Ba(OH)2). NaOH solutions require added BaCl2 or SrCl2; CaCl2 and MgCl2 are less effective. Arginine gives a red color in vitro, detectable to about 2.7 mg/100 ml; alike in NaOH and Ba(OH)2, red colors appear also with guanidine and protamine; other amino acids give green to yellow colors at pH 13. Intrusion of brown into the color reaction is retarded by exclusion of air. Dehydration and mounting procedures are well tolerated; stains appear stable for some months at least.