Preparation of Deoxynucleosides, Purine and Pyrimidine Bases and Deoxyribose 1-Phosphate from Deoxyribonucleic Acid Employing Salmon Enzyme Systems

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Abstract
A crude enzyme system made by treating aqueous extracts of salmon kidney with protamine solution, followed by centrifugation to remove precipitated ribonucleic acid, was used to hydrolyze salmon deoxyribonucleic acid. When such hydrolyses were conducted in presence of toluene to minimize bacterial action, the deoxynucleosides of thymine, uracil, guanine and hypoxanthine were isolated in comparatively pure state. However, the digests also contained a significant proportion of unidentified non-nucleotide ultraviolet-absorbing substances. Digestions carried out in absence of toluene, with accompanying bacterial activity, resulted in formation of thymine, uracil, hypoxanthine and xanthine, which were isolated and characterized. A crude nucleoside phosphorylase enzyme was prepared from salmon livers by a method similar to that used with the kidney enzyme system. In presence of 0.2M KF it exhibited the following order of specificity: deoxyuridine > thymidine > deoxyguanosine > deoxycytidine > deoxyinosine > deoxyadenosine > uridine > cytidine > adenosine > inosine > guanosine > xanthosine. This preparation also exhibited marked phosphodeoxyribomutase and phosphoribomutase activities. Dicyclohexylammonium deoxyribose 1-phosphate was isolated in an amorphous form (purity 74%) from a reaction mixture containing thymidine, orthophosphate and the liver enzyme.