TY - JOUR
T1 - Isoelectric focusing in low-denaturing media
T2 - Visualization in renal disease of variation of the isoelectric point of albumin not related to a remarkable conformational variation
AU - Candiano, G.
AU - Ghiggeri, G. M.
AU - Delfino, G.
AU - Queirolo, C.
AU - Vecchio, G.
PY - 1986
Y1 - 1986
N2 - The isoelectric properties of serum and urinary albumin from normal subjects and patients with nephrotic syndrome have been investigated in various conditions of denaturation, obtained by using urea (0-8 M) as a support in isoelectric focusing. In normal human serum, albumin is rather acidic (pI = 4.7) when focused in glycerol while the denatured form obtained by exposing the protein to 8 M urea has a much higher pI (6.1). Albumin from nephrotic patients is acidic in glycerol but at very low levels of urea (2 M) it shifts from pI 4.7 to pI 6.1; the same effect has been induced by treating albumin with activated charcoal at low pH. In order to obtain more information on urea-induced changes, we have recorded the circular dichroic spectra of albumin when exposed to the concentration of urea used in gels, and we found that no conformational transition occurs for urea concentrations <5 M. Taken together, these observations reveal that variation of the pI of albumin in nephrotic syndrome occurs mainly due to a dissociating effect of urea on charged substances bound to this protein.
AB - The isoelectric properties of serum and urinary albumin from normal subjects and patients with nephrotic syndrome have been investigated in various conditions of denaturation, obtained by using urea (0-8 M) as a support in isoelectric focusing. In normal human serum, albumin is rather acidic (pI = 4.7) when focused in glycerol while the denatured form obtained by exposing the protein to 8 M urea has a much higher pI (6.1). Albumin from nephrotic patients is acidic in glycerol but at very low levels of urea (2 M) it shifts from pI 4.7 to pI 6.1; the same effect has been induced by treating albumin with activated charcoal at low pH. In order to obtain more information on urea-induced changes, we have recorded the circular dichroic spectra of albumin when exposed to the concentration of urea used in gels, and we found that no conformational transition occurs for urea concentrations <5 M. Taken together, these observations reveal that variation of the pI of albumin in nephrotic syndrome occurs mainly due to a dissociating effect of urea on charged substances bound to this protein.
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U2 - 10.1016/S0378-4347(00)83283-1
DO - 10.1016/S0378-4347(00)83283-1
M3 - Article
C2 - 2420813
AN - SCOPUS:0022595496
VL - 374
SP - 279
EP - 288
JO - Journal of Chromatography B: Biomedical Sciences and Applications
JF - Journal of Chromatography B: Biomedical Sciences and Applications
SN - 1387-2273
IS - C
ER -