Incorporation of N15-1-Aspartic Acid into the Abnormal Serum and Urine Proteins of Multiple Myeloma (Studies of the Inter-Relationship of these Proteins)1

Abstract

To ascertain the nature of the interrelationship between abnormal serum globulin and abnormal (Bence-Jones) urinary protein in a patient with multiple myeloma, N15-labeled aspartic acid was administered and the isotope turnover in these proteins followed. The turnover rate of the Bence-Jones protein was extremely rapid, with a half-life of 1.5 days, that of the myeloma serum globulin was much slower (half-life - 21 days). These data are considered incompatible with the hypothesis that Bence-Jones protein is a product of the breakdown of serum globulin. Other possible interrelationships are considered.