Abstract
Aceton-dried powder of equine platelets was extracted with 10mM carbonate buffer at pH 10.5 The extracted protein was precipitated at its isoelectric point (pH 4.45) and followed by ammonium sulfate precipitation (15-35%) to make pure.
The purified protein showed the characteristics as follows: 1) The relative viscosity of the pH 10.5 extract was increased after dialysis against the buffer at pH 8.0, but the addition of KCl and MgCl2 caused an immediate decrease in viscosity. 2) Under an electronmicroscope, the short tubular structure was observed in both positive and negative stained samples at pH 8.0. And the addition of salt caused a side-by-side aggregation. 3) The purified protein incubated with platelet myosin-A showed a low superprecipitation activity at low ionic strength, in the presence of Mg++ and ATP, but the degree was much weaker than that of synthetic platelet actomyosin. 4) On the basis of its electrophoretic mobility, the molecular weight was calculated to be about 50, 000. From those results, it seemed that tubulin-like protein was extracted from aceton-dried powder, though an immunochemical demonstration was not carried out.
By our method described in this paper, it became possible to reserve the sample much longer, so that it is expected that the biochemical study about microtubulus in blood cells will be made more progress.
