Adenylic acid, deamination formation

Adenylic deaminase. The deamination of 5 -adenylic acid by 5 -adenylic deaminase results in the formation of 5 -inosinic acid. This process, applied to mushrooms, intensifies the natural flavor (53). 

When RNA of tobacco mosaic virus is incubated with nitrous acid, changes occur in the base composition because nitrous acid deaminates cytosine and adenine. (It also deaminates guanine, but not in the intact virus.) Cytosine is converted to uracil and adenine is converted to hypoxanthine (adenylic acid inosinic acid). Consequently, the six amino groups of adenine and cytosine are replaced by keto groups. Since the complementariness of the newly synthesized RNA chain is dictated by the formation of hydrogen bonds with the bases in the template, the newly synthesized RNA is different from the wild RNA and thus a base mutation has been introduced experimentally. 

The possibility existed that adenylic acid might have been the first purine compound synthesized by the homogenate, and that the isolated inosinic acid was merely a deamination product of adenylic acid. However, labeled formate was not incorporated into the adenine nucleotides of the homogenate or into added adenylic acid. 

Some common examples of enzymes inhibited by phosphate ions include carboxypeptidase, fumarase, urease, phos-phoglucomutase, carboxylase, arylsulphatase and muscle deaminase (for the deamination of adenylic acid). Frequently this inhibition is due to competition of the phosphate with substrates containing phosphate groups or to complex formation with a metal ion essential for the enzyme activity. 

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