Aromatic amino acid decarboxylase: pH-dependence of substrates and inhibitors [proceedings].

with 50 % (v/v) ethanol and radioactivity determined by liquid-scintillation counting. The separation procedure used is capable of separating cyclic AMP from all known naturally occurring adenine nucleotides. Results showed that the ‘total‘ membrane fraction from barley leaves possesses adenylate cyclase activity equivalent to 26pmol of cyclic AMP formed/min per mg of membrane protein. The lOOO00g supernatant possessed negligible adenylate cyclase activity. Constancy of the 3H/14C ratio of the isolated sample through several purification steps (Table 1) and during hydrolysis by ox heart phosphodiesterase confirms that the product of the enzymic activity determined is cyclic AMP.