Figure 2.

Profile of purification by caesium chloride density-gradient ultracentrifugation of an HIV positive MUC7 sample. Freeze dried material, in this example a sample of MUC7 (V₀), was dissolved in 4 M GuHCl containing 10 mM EDTA, 5 mM NEM, and 0.05% CHAPS pH 6.5, and adjusted to a density of 1.39 to 1.40 g/ml with solid caesium chloride. Density-gradient centrifugation was performed in a Beckman L45 ultra-centrifuge for 48 h at 40 000 rpm/105 000 g, at 4°C. Fractions 3 and 4 were pooled, dialysed against 3 changes of distilled water overnight at 4°C and freeze-dried.