Purification and Some Properties of Adenosine (Phosphate) Deaminase from the Liver of the Squid Todarodes pacificus

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An enzyme that catalyzed the deamination of adenosine 3'-phenylphosphonate was purified from squid liver to homogeneity as judged by SDS-PAGE. The molecular weight of the enzyme was estimated to be 60,000 by SDS-PAGE and 140,000 by Sephadex G-150 gel filtration. The enzyme deaminated adenosine, 2'-deoxyadenosine, 3'-AMP, and 2', 3'-cyclic AMP, but not adenine, 5'-AMP,3',5'-cyclic AMP, ADP, or ATP. The apparent K_m and V_<max> at pH 4.0 for these substrates were comparable (0.11-0.34 mM and 179-295μmol min^<-1> mg^<-1>, respectively). The enzyme had maximum activity at pH 3.5-4.0 for adenosine 3'-phenylphosphonate, at pH 5.5 for adenosine and 2'-deoxyadenosine, and at pH 4.0 for 2',3'-cyclic AMP and 3'-AMP when the compounds were at concentration of 0.1 mM. The K_m at 4.0 and 5.5 for each substrate varied, but the V_<max> were invariant. These results indicated that the squid enzyme was a novel adenosine (phosphate) deaminase with a unique substrate specificity.
社団法人日本農芸化学会の論文
1995-07-23