THE HETEROGENEITY OF GAMMA-GLOBULIN IN POST-EXERCISE URINE
Post-exercise urine was collected and the protein was precipitated with ammonium sulphate. The γ-globulin was separated from other urinary proteins by preparative starch block electrophoresis. The γ-globulin was then separated by gel filtration into two fractions, the faster one consisting mainly of 7 S γ-globulin while the slower one contained "low molecular weight" γ-globulin sedimenting at 3.5 S. The low molecular weight γ-globulins were further fractionated on CM-Sephadex to yield four fractions. Each of the chromatographic fractions was shown to be heterogeneous by starch gel electrophoresis at pH 4. The same degree of heterogeneity was observed in preparations of pooled urinary γ-globulin and γ-globulin from a single individual. The two major electrophoretic components of each chromatographic fraction formed precipitates in agar diffusion tests with antiserum to 7 S γ-globulin and to the L-polypeptide chain of 7 S γ-globulin. Two chromatographic fractions reacted with antiserum to the H-polypeptide chain of 7 S γ-globulin. All of the fractions failed to react with antiserum to β2A-globulin and β2M-globulin. Amino acid analysis showed distinct differences among the chromatographic fractions. One of the fractions closely resembled the L-chain of 7 S plasma γ-globulin with respect to amino acid composition. After reduction of disulphide bonds and alkylation most of the urinary γ-globulin resembles L-chain in electrophoretic behavior. The γ-globulins of post-exercise urine were found to be qualitatively similar to the γ-globulins of normal urine but post-exercise γ-globulins were present quantitatively in much larger amounts.