Precipitation and characterization of an aluminosilicate from AlCl3-Na2SiO3-HCl in serum, of interest for Alzheimer disease.
A precipitation experiment was performed with human serum to model aluminosilicate formation in brains of patients with Alzheimer disease. Aluminum and (or) silicate ions were added to serum in a 1:2 molar ratio at pH 7.4. Precipitates formed immediately and were left for 24 h at 37 degrees C before filtration. Silicate and aluminosilicate formed precipitates with human serum proteins albumin, transferrin, and IgG. In untreated samples, the IgG/albumin ratio increased slightly compared with the ratio in dried serum. Diethylbarbiturate-washed precipitates had a significantly lower protein content than did untreated ones. The IgG/albumin ratio increased considerably in the sample containing aluminosilicate. We conclude that IgG is the sodium dodecyl sulfate-soluble human protein most firmly bound to the aluminosilicate matrix. From 27Al magic-angle-spinning nuclear magnetic resonance (MAS NMR), a pronounced peak was found at 52.79 ppm and a minor peak at 0.53 ppm, suggesting that 4-coordinated aluminum predominates and that 6-coordinated aluminum is present in a smaller proportion. The 29Si MAS NMR spectrum shows a poorly ordered structure. The aluminosilicate formed also contains the cations Na+ > K+ > Ca2+ > Mg2+ and anions Cl- > PO4(3-). Rather than looking for aluminum toxicity to explain the effects of Alzheimer disease, one should consider that by precipitating such a composite phase, the balance of cations, anions, and proteins in human serum is changing.
Bilinski
H
H
Ruder Boskovic Institute, Zagreb, Croatia.
Horvath
L
L
Trbojevic-Cepe
M
M
D000535:Aluminum / Q000097:blood* / Q000737:chemistry; D000077410:Aluminum Chloride; D017607:Aluminum Compounds; D000538:Aluminum Silicates / Q000097:blood* / Q000737:chemistry / Q000378:metabolism; D000544:Alzheimer Disease / Q000378:metabolism*; D000838:Anions; D001798:Blood Proteins / Q000737:chemistry / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D002412:Cations; D011232:Chemical Precipitation; D002712:Chlorides / Q000097:blood* / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism; D017640:Silicates; D012824:Silicic Acid / Q000097:blood* / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D014168:Transferrin / Q000737:chemistry / Q000378:metabolism; D014961:X-Ray Diffraction
D017607:Aluminum Compounds; D000538:Aluminum Silicates; D000838:Anions; D001798:Blood Proteins; D002412:Cations; D002712:Chlorides; D007074:Immunoglobulin G; D012709:Serum Albumin; D017640:Silicates; D014168:Transferrin; D012824:Silicic Acid; C049037:aluminosilicate; D000077410:Aluminum Chloride; D000535:Aluminum; C005691:sodium silicate