Evidence of a thromboxane A2-Ca2+ complex: a conformational approach.

Thromboxane A2 has been proposed as an ionophore capable to transport calcium from the platelet dense tubular system to the cytoplasm to activate the contractile proteins. However the half-life (30 sec.) of this compound limits considerably the experimental approach. The conformational analysis is proposed here as a possible way to identify such transient conformations. We bring evidence of the existence of two Ca2+-thromboxane A2 isomeric complexes: one structure responsible for the complexation-decomplexation process at the interface and one lipophilic structure able to cross the lipid membrane.