Solubility of serum amyloid A. Detection of serum amyloid A (SAA) isoforms (by isoelectric focusing and immunostaining) (A) and assessment of presence of non-SAA impurities in each of the dissolutions analyzed in A (by sodium dodecyl sulphate polyacryl amide gel electrophoresis and silverstaining) (B) following dissolution of freeze-dried equine acute phase serum in 70% 2-propanol (lane 1), 8 M urea (lane 2), and Milli-Q water (lane 3). SAA isoform pattern (A) and protein content (B) in untreated equine serum is seen in lane 4. The molecular weights (MW) of the BioRad standard are given to the right (S). SAA isoforms were detected in all solutes (A), but the most preserved isoform pattern of SAA was observed after dissolution of freeze dried serum in 8 M urea (lane 2).