Size exclusion chromatography of equine serum amyloid A. Detection of serum amyloid A (SAA) isoforms and assessment of purity of SAA separated by size exclusion chromatography of freeze-dried equine acute phase serum dissolved in Milli-Q water. A: Immunostained isoforms of SAA after isoelectric focusing of size exclusion chromatography fractions 9–11. Note the incomplete isoform pattern compared to the SAA detected in freeze-dried serum dissolved in Milli-Q water (M, Figure 2A, lane 3), and note the detection of SAA in fraction 9, corresponding to a molecular weight of 237 kDa. No SAA was detected in the other 41 fractions. B: Silverstained gel following sodium dodecyl sulphate polyacryl amide gel electrophoresis (SDS-PAGE) for the assessment of presence of non-SAA impurities in the fraction analyzed in A. The molecular weights (MW) of the BioRad standard (S) are given to the left.