(n) (biochemistry) a nucleoside that is a structural component of nucleic acids; it is present in all living cells in a combined form as a constituent of DNA and RNA and ADP and ATP and AMP
(n) an enzyme found in mammals that can catalyze the deamination of adenosine into inosine and ammonia, Syn. ADA, Example:ADA deficiency can lead to one form of severe combined immunodeficiency disease; the gene encoding ADA was one of the earlier human genes to be isolated and cloned for study