Extraction of uraemic toxins with activated carbon restores the functional properties of albumin.
BACKGROUND
Previous work has demonstrated that a partial normalization of the conformation of albumin from uraemic plasma and a substantial restoration of its binding abilities can be achieved by extraction with activated charcoal. This is best achieved at pH 3, but exposure of whole plasma to this low pH leads to the loss of some essential components.


METHODS
The melting curves and ligand-binding abilities of uraemic albumin have been investigated after extraction with a new generation of activated carbon at three pH values (7.2, 3.0 and 5.08).


RESULTS
Albumin isolated from uraemic plasma had a characteristically increased melting temperature because of bound ligands. Extraction of uraemic plasma at pH 7.2, 5.08 and 3.0 induced low-temperature shifts of albumin thermo-adsorption maximum T1 of 1.4, 3.8, 2.4 degrees C and T2 of 0.8, 3.9 and 1.2 degrees C, respectively. Flow microcalorimetry data demonstrated a decrease in the ability of uraemic albumin to bind octanoate, phenol red, salicylic acid, warfarin and diazepam. Purification of uraemic plasma at pH 5.08 completely restored the binding affinity of albumin for all the marker ligands.


CONCLUSIONS
Highly efficient activated carbons, with clinically feasible acidification of plasma, can remove strongly albumin-bound uraemic toxins. Investigation of the melting curve of the isolated albumin is a new biophysical way to monitor both its molecular condition and the extent of removal of protein-bound toxins by dialysis. The melting curve provides new qualitative and quantitative information about albumin in an analogous way to an electrocardiogram and the heart.
Sarnatskaya
Veronika V
VV
Section of Artificial Organs, Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology of The National Academy of Sciences, Kiev, Ukraine.
Lindup
W Edward
WE
Ivanov
Adrej I
AI
Yushko
Larisa A
LA
Tjia
John
J
Maslenny
Vitaly N
VN
Gurina
Natalia M
NM
Nikolaev
Vladimir G
VG
D000143:Acids / Q000737:chemistry; D000328:Adult; D002151:Calorimetry / Q000379:methods; D002606:Charcoal / Q000737:chemistry*; D002846:Chromatography, Affinity; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008297:Male; D008875:Middle Aged; D011485:Protein Binding / Q000502:physiology; D012016:Reference Values; D012709:Serum Albumin / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D013816:Thermodynamics; D014118:Toxins, Biological / Q000737:chemistry*; D014511:Uremia / Q000097:blood*
D000143:Acids; D008024:Ligands; D012709:Serum Albumin; D014118:Toxins, Biological; D002606:Charcoal