DEAMINATION OF ADENINE AND RELATED COMPOUNDS AND FORMATION OF DEOXYADENOSINE AND DEOXYINOSINE BY LINGCOD MUSCLE ENZYMES

Abstract

Adenylic acid deaminase was destroyed by heating crude extracts of lingcod muscle to 58 °C, while deamination of adenosine and deoxyadenosine was unaffected. Deoxyadenosine was deaminated about 2300 times as fast as adenine by the enzyme extract. The specific activity of the purine nucleoside phosphorylase with adenine and deoxyribose-1-phosphate as substrates was similar to that of the deoxyadenosine deaminase of the enzyme preparations. It can thus be stated with certainty that adenine is a substrate for the nucleoside phosphorylase, that deoxyadenosine thus formed is promptly deaminated to deoxyinosine, and that deamination of adenine to hypoxanthine plays a negligible role in formation of deoxyinosine. The presence of small amounts of deoxyadenosine in the above reaction was verified by radioactive adenine and isolation of deoxyadenosine of constant specific activity by addition of deoxyadenosine carrier.