1 1 2 11 buffer + 0.9 M (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> (7 ml) to buffer (7 ml) hydrophobic interaction column chromatography (GE Healthcare UK Ltd., RESOURCE PHE) 0.27 M (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> 50 mM NaPi, pH 7.0 crib220u270rib220u36164i Column chromatography _