Characterization of plastocyanin from corn (Zea mays L.) and pea (Pisum sativum L.) leaves.

A comparison of plastocyanin isolated from pea and corn leaves was made according to a number of indices. No appreciable differences were detected between the proteins in molecular weight or sedimentation constants. In addition, it was shown that plastocyanin of corn, in comparison with the pea protein, possesses greater thermal stability, is more resistant to the action of high and low H+ ion concentrations, as well as to the action of concentrated solutions of urea and guanidine nitrate. The detected differences indicate peculiarities in the molecular organization of plastocyanins from various groups of plants. It is suggested that the differences noted in the structure of plastocyanins can ensure effective functioning of proteins under nonuniform conditions of the external environment.