Calcium-45 binding by human prealbumin

¹ Radioisotope Service, Veterans Administration Hospital, and Department of Medicine, University of Oklahoma School of Medicine, Oklahoma City, Oklahoma

Calcium-45 binding by human albumin and prealbumin has been studied. Protein separation was performed by continuous paper electrophoresis. Calcium-45 was added to the fractions and the mixture incubated at 37°C for 24 hours. Unbound calcium-45 was removed by dialysis against tap water for 16 hours, the pH of the fractions remained between 8.6–9.1 at all times. Aliquots of the fractions were then counted with a micromil gas flow counter. The greatest specific activity was found in several tubes preceding the albumin, i.e. with faster electrophoretic mobility than classical albumin. The calcium-binding ability of this fraction, which has been previously called ‘prealbumin,’ exceeded that of classical albumin by sixfold.