Comparison of the properties of two kinds of preparations of human blood platelet actin with sarcomeric actin.
A new procedure of purification of actin from human blood platelets was used. This method starting from acetone powder of whole platelets gives a much higher yield than the one previously described (actin I) (Landon et al. (1977) Eur. J. Biochem., 81, 571-577). This actin II preparation has the same reduced viscosity as skeletal muscle actin, while the reduced viscosity of actin I preparation is about 1/10 of this value. Moreover actin I has the form of very short filaments as shown by electron microscopy. After an extra step of purification actin I, when polymerized, acquired a high reduced viscosity. We confirmed that platelet and sarcomeric actins are similar in their polymerization properties and their ability to activate muscular myosin. A circular dichroism study showed that the overall conformation of both actins are similar, but the environment of their aromatic chromophores is different.
D000199:Actins / Q000097:blood / Q000302:isolation & purification / Q000494:pharmacology*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001792:Blood Platelets / Q000032:analysis*; D017301:Ca(2+) Mg(2+)-ATPase; D002942:Circular Dichroism; D004789:Enzyme Activation; D006801:Humans; D046911:Macromolecular Substances; D009210:Myofibrils / Q000032:analysis*; D011487:Protein Conformation; D011817:Rabbits; D012518:Sarcomeres / Q000032:analysis*; D014783:Viscosity
D000199:Actins; D046911:Macromolecular Substances; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase