Summary
Four primary fractions comprising at least 97 per cent of the plasma proteins have
been critically appraised for evidence of denaturation arising from a low temperature—low
ionic strength fractionation system. The results in addition to those referable to
the recovery of mass and biological activity include the following: The high solubilities
of these fractions at pH 7.3 and low ionic strengths; the compatibility of the electrophoretic
and ultracentrifugal data of the individual fractions with those of the original plasma;
and the recovery of hemoglobin, not hematin, in fraction III obtained from specimens
contaminated with this pigment. However, the most significant evidence for minimum
alterations of native proteins was that the S20, w and the electrophoretic mobility data on the physically recombined fractions were
identical to those found on whole plasma.
The fractionation procedure examined here quantitatively isolates fibrinogen, prothrombin
and antithrombin in primary fractions. Results have been obtained demonstrating its
significance in other biological systems. These include the following: The finding
of 5 S20, w classes in the 4 primary fractions; the occurrence of more than 90 per cent of the
plasma gamma globulins in fraction III; the 98 per cent pure albumin in fraction IV;
and, finally, the high concentration of beta lipoproteins in fraction II.
