Salt-precipitation method does not isolate to homogeneity Tamm-Horsfall glycoprotein from urine of proteinuric patients and pregnant women.
OBJECTIVE
Assessment of the degree of purification of Tamm-Horsfall glycoprotein from anomalous urine.


METHODS
Two methods have been compared: the method of Tamm & Horsfall (T&H method) consisting in the precipitation of THP by the addition to urine of NaCl up to 0.58 mol/L and the filtration of urine through a diatomaceous earth filter (DEF method) in which THP is selectively trapped because of its gelation/aggregation tendency. The purity of THP preparations has been evaluated by SDS-PAGE analysis and Western blotting developed with anti immunoglobulin G (IgG) antibodies and antichorionic gonadotropin antibodies.


RESULTS
All THPs isolated by T&H method from proteinuric patients were contaminated by IgG and one of the five preparations from pregnant women even by chorionic gonadotropin. A smaller or no contamination was found in THPs isolated by DEF method.


CONCLUSIONS
Although albumin is the most abundant protein in the anomalous urine, it never appears in THP preparations. The consistent contamination with IgG of THP prepared by salt precipitation-method might be related to the formation of a stable complex between the two proteins.
Cavallone
Daniela
D
Department of Experimental Pathology, University of Bologna, Via S Giacomo 14, 40126 Bologna, Italy.
Malagolini
Nadia
N
Frascà
Giovanni-Maria
GM
Stefoni
Sergio
S
Serafini-Cessi
Franca
F
D000818:Animals; D015153:Blotting, Western; D011232:Chemical Precipitation; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000302:isolation & purification / Q000652:urine; D007674:Kidney Diseases / Q000652:urine; D009088:Mucoproteins / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification* / Q000652:urine*; D011247:Pregnancy; D011507:Proteinuria / Q000652:urine*; D011817:Rabbits; D012492:Salts / Q000737:chemistry*; D058949:Uromodulin
D007074:Immunoglobulin G; D009088:Mucoproteins; D012492:Salts; C548612:UMOD protein, human; D058949:Uromodulin