3.4.21.36 - 29635, 34994, 36558, 36559, 36560, 36562, 36563, 36565, 36568, 36572, 36577 3.4.21.36 ammonium sulfate precipitation and ion exchange chromatography 697474 3.4.21.36 chromatofocusing and Superdex-75 gel filtration 669505 3.4.21.36 nickel-affinity chromatography 754151 3.4.21.36 two forms: EI and EII 36571