The water content of the particle of vaccinia virus proteid

Abstract

When vaccinia virus proteid particles agglutinated in a weakly acid solution were centrifuged by an ordinary centrifuge for a long period of time, and the water contents of the precipitate thus sedimented were measured successively after every period of centrifuging, then it was found that the water content of the sediment diminished rapidly at the beginning of the centrifuging, but that at later periods of sedimentation the diminution rate became low and constant, decreasing rectilinearly. If we assume that the decrease in the water content with a constant rate is due to the squeezing out the water contained in the particle itself and that the rapid decrease at the beginning of the centrifugation with an inconstant rate is due to the pressing out of the water interposing among proteid particles, the water content of the particle can be estimated by measuring the content at the time when the decreasing rate becomes constant. From this point of view, the proteid particles are estimated as containing about 90% water. In the same way coli-phage proteid particles are found to have a similar water content. Sugar-insoluble space of the proteid particle was calculated by measuring the quantity of sugar added to the suspension of elementary bodies which were centrifuged off after the addition of the sugar; the water content was estimated from this sugar-insoluble space to be likewise about 90%, although the space varies over a wide range with the concentration of sugar added. Also from the viewpoint of the filtrability of the particles it is reasonable to consider that they strongly swells on absorbing water of about 10 times as great as its mass. These conclusions can be applied also generally to minute-bodyforming proteid (protoplasm-lipoproteid particles) having no virus activity.