Conformational Transitions and Glycation of Serum Albumin in Patients with Minimal-Change Glomerulopathy

BACKGROUND: There has been a lack of study on the structural changes of serum albumin in patients with minimal change disease (MCD). To determine whether glycation and/or conformational transitions of albumin are involved in the pathogenesis of albuminuria, nine patients with MCD were enrolled in a prospective follow-up study for comparison of these parameters in serum albumin during the remission and relapse of nephrotic syndrome. METHODS: Circular dichroism measurements were made with purified albumin. Ellipticities at each wavelength were transformed to mean residue ellipticity. Monosaccharide composition was analyzed by high-pH anion-exchange chromatography with pulsed amperometric detection. RESULTS: There was no difference in the proportions of α-helix, β-conformation, and β-turn of albumin between the sera of control patients and those with nephrotic syndrome. However, the proportion of the random configuration was slightly higher in the plasma albumin of patients in relapse than in those in remission. The proportion of the random configuration was lower in the albumin of the serum than in the urine of patients with nephrotic syndrome, but there was no difference in the proportions of α-helix, β-conformation, and β-turn of albumin between their plasma and urine. CONCLUSION: Our results suggest that conformational changes in albumin are involved in albuminuria in patients with MCD.