| Abstract: | A method has been studied to investigate the purine and pyrimidine derivatives of milk from cows on normal feed and protein-free feed, by deproteinization with TCA1, extraction of ether-soluble material, treatment with active charcoal for purification, fractionation of the eluate by the method of Le Page, finally identification by the ion-exchange thin-layer chromatography. The composition of the purine and pyrimidine derivatives of milk produced by protein-free cows and by normally fed cows was about the same: predominantly orotic acid and several minor components, mainly CMP, UMP, traces of adenosine derivatives, and other not definitely identified compounds. Uric acid could not be estimated due to its low solubility and complete retention on the charcoal. Total UV-absorption at 280 nm for normal feed milk serum was between 4200–4700 O.D.U./l while protein-free milk serum gave different values between 3600–6900 O.D.U./l. |
