Urinary protein was obtained from 60 patients suffering from chronic nephritis, nephrotic syndrome, diabetes mellitus or pyelonephritis. The protein was fractionated (Diaflo filter paper) to be devided into proteins of different molecular size, those of less than 50,000 of M.W. and those of 50,000-100,000. Each protein fraction was examined by immunoelectrophoresis, single radial immunodiffusion techniques and ultracentrifugation. The proteins below 50,000, in M.W. consisted of albumin, α
1-glycoprotein, transferrin and Ig-G. The proteins ranging from 50,000 to 100,000 consisted of albumin, and α
1-glycoproten.
The major constituents of the γ-globulin fraction in human urine appeared to be one fifth to one sixth of the serum γ-globulin in size and has coefficient of approximately 2.0S. This low molecular weight fragment of γ-globulin was antigenically closely related to serum 7S-γ-globulin. Also, the molecule size of the albumin in urin was about half of the serum albumin and showed a coefficient of approximately 1.8S. The possibility that the fractions represent naturaly breakdown products of plasma proteins was discussed.
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