Acyl-CoA synthetase catalyzes the synthesis of diadenosine hexaphosphate (Ap 6A)

The synthesis of diadenosine hexaphosphate (Ap 6A), a potent vasoconstrictor, is catalyzed by acyl-CoA synthetase from Pseudomonas fragi. In a first step AMP is transferred from ATP to tetrapolyphosphate (P 4) originating adenosine pentaphosphate (p 5A) which, subsequently, is the acceptor of another AMP moiety from ATP generating diadenosine hexaphosphate (Ap 6A). Diadenosine pentaphosphate (Ap 5A) and diadenosine tetraphosphate (Ap 4A) were also synthesized in the course of the reaction. In view of the variety of biological effects described for these compounds the potential capacity of synthesis of diadenosine polyphosphates by the mammalian acyl-CoA synthetases may be relevant.