Transitions of serum albumin in patients with glomerulosclerosis 'in vivo' characterization by electrophoretic titration curves

Maurizio Bruschi, Luca Musante, Giovanni Candiano, Laura Santucci, Cristina Zennaro, Michele Carraro, Piero Del Boccio, Rosanna Gusmano, Francesco Perfumo, Andrea Urbani, Gian Marco Ghiggeri

Research output: Contribution to journalArticlepeer-review

Abstract

HSA functions as a physiological transporter of solutes and small molecules that induce structural transitions 'in vitro'. Analysis of these transitions requires prior purification of HSA that could introduce bias due to conformational changes. We utilized electrophoretic titration curves to describe a neutral to acid (N-A) transition of HSA directly in sera of seven patients with active focal segmental glomerulosclerosis (FSGS). The divergent electrophoretic profile of HSA was characterized by a shift in the range of pHs between 4.5 and 7.5 with an average variation of free electrophoretic mobility corresponding to loss of 1 positive charge in the pKa protonation range of histidyl residues and should involve domain I of HSA. 'In-gel' determination by maleimide-PEO2-biotin of free SH 34 of domain I showed inaccessibility of the dye at this site in pathological HSA and alkylation with the same complex induced N-A transition in normal HSA. Potential binders of free imidazoles such as Ca++ and/or of SH 34 such as NO were excluded on the basis of direct titration and studies on binding stimulation. This is the first report describing a transition of HSA directly 'in vivo', and the utilization of electrophoretic titration curves was critical to this purpose. This transition appears to be specific to FSGS and is unrelated to the nephrotic syndrome, Ca++ and NO binding. Spectroscopic analysis will elucidate the structural implication.

Original languageEnglish
Pages (from-to)2960-2969
Number of pages10
JournalElectrophoresis
Volume27
Issue number14
DOIs
Publication statusPublished - Jul 2006

Keywords

  • Albumin
  • Electrophoretic titration curves
  • Focal segmental glomerulosclerosis
  • Nephrotic syndrome

ASJC Scopus subject areas

  • Clinical Biochemistry

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