Amino acid sequence of a modified beta 2-microglobulin in renal failure patient urine and long-term dialysis patient blood.

We isolated and analyzed beta 2-microglobulin (BM) in urine of two renal failure patients and in ultrafiltrate from long-term dialysis patients. In both groups of patients, we found the native BM with pI 5.7 and some modified BM with pI 5.3. The amino acid sequence of the modified BM was determined and compared with that of the native BM; the N-terminal isoleucine residue was missing and the second glutamine residue was cyclized into pyroglutamic acid in the modified BM.