Separation and identification of the uremic middle molecules

Sera and urine from patients with severe uremia and healthy persons were separated by means of gel permeation chromatography on Sephadex G-15 column with N(C₂H₅)₃-H₂CO₃ buffer as the eluent. Two middle molecular peaks(A and B) were detected at 206 nm in normal urine, uremic serum and uremic urine, but these two peaks were hardly observed in the profile of normal sera. In contrast, the absorption at 206 nm of fractions A and B from uremic urine were smaller than that of fractions A and B from normal urine. Fractions A from normal urine, uremic serum and urine were collected and resolved into 3 subpeaks at 254 nm by high performance liquid chromatography. Two of these subpeaks, A- I and A- I, were detected in uremic serum, normal urine and uremic urine. The results of MALDI-TOF-MS revealed that the fraction A- I from both uremic serum and normal urine contained a component with molecular weight 1214, which could hardly be seen in the fraction A- I of uremic urine.