PURINES AND PTERIDINES FROM THE REFLECTING PIGMENT OF THE ARTHROPOD RETINA

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Abstract
The chemical nature of the retinal reflecting pigment in Homarus and Limulus was studied. This pigment has been thought to be guanine in crustaceans, but the properties of the pigment from Homarus do not agree with those for guanine. Paper partition chromatography reveals 5 components in lobster reflecting pigment, 3 being absorbent and 2 fluorescent in short-wave UV light. Histochemical treatment of sections with methenamine-silver, incubation of pigment with uricase, and comparisons of the Rf indices of the 3 UV-absorbent components with those of reference purines show them to be uric acid, xanthine, and hypoxanthine. Identifications were verified by determining the UV absorption spectra of eluates of the retinal purines from paper chromatograms. One of the 2 UV-fluorescent components is xanthopterin. The second fluorescent compound is probably a pteridine its absorption spectrum in 0.1 [image] HCl shows maxima at 245 m[mu] and 353 m[mu]; in 0.1 [image] NaOH these maxima are 255 m[mu] and 390 m[mu]. Retinal reflecting pigment in Limulus is guanine.