title: Transitions of serum albumin in patients with glomerulosclerosis 'in vivo' characterization by electrophoretic titration curves.
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.
authors.affiliation: KIDneyFOUNDation for Renal Research in Children, Genoa, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bruschi
authors.forename: Luca
authors.initials: L
authors.lastname: Musante
authors.forename: Giovanni
authors.initials: G
authors.lastname: Candiano
authors.forename: Laura
authors.initials: L
authors.lastname: Santucci
authors.forename: Cristina
authors.initials: C
authors.lastname: Zennaro
authors.forename: Michele
authors.initials: M
authors.lastname: Carraro
authors.forename: Piero
authors.initials: P
authors.lastname: Del Boccio
authors.forename: Rosanna
authors.initials: R
authors.lastname: Gusmano
authors.forename: Francesco
authors.initials: F
authors.lastname: Perfumo
authors.forename: Andrea
authors.initials: A
authors.lastname: Urbani
authors.forename: Gian Marco
authors.initials: GM
authors.lastname: Ghiggeri
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001797:Blood Protein Electrophoresis; D002648:Child; D005260:Female; D005923:Glomerulosclerosis, Focal Segmental / Q000097:blood* / Q000175:diagnosis; D006801:Humans; D008297:Male; D009404:Nephrotic Syndrome / Q000097:blood* / Q000175:diagnosis; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D012709:Serum Albumin / Q000032:analysis* / Q000737:chemistry; D017186:Titrimetry
chemical_list: D012709:Serum Albumin