[Isolation and study of certain properties of caldesmon from cattle aorta]

A modified method for bovine aorta caldesmon isolation has been developed. When isolated from large vessels, caldesmon is copurified with connective tissue proteins whose molecular weight is similar to that of caldesmon. Separation of these proteins can be achieved by stepwise anion- (Q-Sepharose) and cation (phosphocellulose)-exchange chromatography. Bovine aorta and duck gizzard caldesmons have similar apparent molecular weights, absorption at 280 nm and one-dimensional peptide maps. Casein kinase II transfers about one mol of phosphate per mol of bovine aorta or duck gizzard caldesmon. In both cases, the sites of phosphorylation are located in the N-terminal peptides of apparent molecular weights of 26-28 kDa. It is concluded that there are no substantial differences between the structures and properties of avian gizzard and mammalian vessel caldesmons.