Conversion of adenosine(5′)oligophospho(5′)adenosines into inosn(5′)oligophospho(5′)inosines by non-specific adenylate deaminase from the snail Helix pomatia

• Published in: Biochimica et biophysica acta. General subjects Vol. 1243; no. 1; pp. 78 - 84
• Main Authors: Guranowski, A., Starzyńska, E., Günther Sillero, M.A., Sillero, A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 18.01.1995
• Subjects: Adenylate deaminase; Ap 4A; Diadenosine polyphosphate; Diinosine polyphosphate; Helix pomatia; Helix pomatia; Ap 4A; Adenylate deaminase; Diadenosine polyphosphate; Diinosine polyphosphate
• ISSN: 0304-4165; 1872-8006
• DOI: 10.1016/0304-4165(94)00110-J

Until now, the catabolism of adenosine(5′)triphospho(5′)adenosine (Ap 3A) and adenosine(5′)tetraphospho(5′)adenosine (Ap 4A) has been thought to commence with either hydrolytic or phosphorolytic cleavage of their oligophosphate chains, depending on the organism. Here, we show that in the extracts from the retractile ‘foot’ of the snail Helix pomatia deamination predominates; the adenosine moieties of these and other adenosine(5′)oligophospho(5′)adenosines (Ap nAs) undergo successive deamination leading, via an inosine(5′)oligophospho(5′)adenosine (Ip nA), to the corresponding inosine(5′)oligophospho(5′)inosine (Ip nI). The reactions are catalyzed by the non-specific adenylate deaminase described earlier (Stankiewicz, A.J. (1983) Biochem. J. 215, 39–44). We describe TLC and HPLC systems which allow the separation of any of the deaminated derivatives from its parent compound; Ap 2A, Ap 3A, Ap 4A or Ap 5A. The K m values for these substrates are 20, 22, 32 and 39 μM, respectively, whereas the K m for 5′-AMP is 12 μM. Relative substrate specificities for these compounds amount to 25, 18, 14, 7 and 100. The enzyme was shown also to deaminate phosphonate and thiophosphate analogues of Ap 3A.