7‐ O ‐hemisuccinyl‐deacetyl forskolin—sepharose: a novel affinity support for purification of adenylate cyclase

Hormonally stimulated adenylate cyclase consists of at least 3 individual components: a receptor (R) which recognizes hormones or neurotransmitters; a GTP-binding component (G-protein, abbreviated G, G/F or N); and a catalytic moiety (C) which generates the second messenger cAMP [1-4]. While considerable progress has been achieved in the purification of the G-protein [5-7] and the fl-adrenergic receptor [8,9] purification of the catalyst is lagging behind. This may in part be explained by its extreme instability and by the lack of suitable ligands for construction of affinity supports which otherwise proved to be extremely useful for isolation of minute quantities of total cellular protein [9,10]. The most notable success in purification of adenylate cyclase has been achieved with the canine myocardial enzyme by successive hydrophobic and affinity chromatography on ATP-agarose [11]. However, the procedure in [11] failed to resolve C and G since the purified material was still activated by Gpp(NH)p. The first successful separation of the catalyst and the regulatory G-protein has been achieved by