Abstract
Purification of macroglobulin from a patient with Waldenström's macroglo-bulinemia was done through gel filtration, and water precipitability of each macroglobul in preparation was assayed by means of the Sia water test. Some other physicochemical properties of the macroglobulin preparation were also examined.
Both above pH 9.2 and below pH 4.7, Sia test was negative and only a little dissociation was observed at faster sedimenting and minor component. Main peak of 15S did not show any dissociation by changing pH. Removal of IgG from Fr M-1 increased water solubility of macroglobulin. Neuraminidase treatment did not cause change in the Sia test, while it reduced the sedimentation coefficients of Fr M-2 from 14.9S and 24.6S to 13.3S. Decrease of sedimentation coefficients to 8.3S and 12.2S by urea treatment did not cause change in the Sia test. These results suggested that association of IgG with macroglobulin decreased water solubility of macroglobulin, and dissociation between macroglobulin and its subunits did not directly relate to water precipi-tability of the protein. The role of high contents of neutral sugar, threonine and serine in the precipitability of macroglobulin was discussed.
