Abstract
Contractile proteins of platelet play an important role in the functions of platelet aggregation or platelet adhesion, and the concentration of calcium has an effect on these functions. Therefore it is considered that there is the factor which regulates the activity of contraction by contractile protein.
In this report, we purified the protein from platelets which inhibits the gelation of actin in the presence of calcium.
Homogenate of human platelets was firstly chromatographied by DEAE Sepharose column with linear gradient of KCl (0.1-0.4M), and secondary by actin binding affinity chromatography column applyed in the presence of 1mM CaCl2 and then eluted with 10mM EGTA containing buffer. This purified protein had remarkable actin gelation inhibitory activity. And this activity appered in the range of 10-7-10-6M of free calcium, which is the concentration of intracellular calcium.
This protein exhibited three bands, molecular weight of 8.5×104, 4.5×104, and 4.3×104, by SDS polyacrylamide gel electrophoresis.
The band of 4.3×104 was thought to be of actin of platelets and the remaining to be of actin gelation inhibitory factor.
