Purification of the human complement control protein C3b inactivator.

摘要: An alternative method of isolation from human plasma is described for C3b inactivator, C3bINA, the proteinase that in conjunction with either beta 1H or C4b-binding protein will hydrolyse respectively C4b, activation products third, C3 and fourth, C4, components complement. The purification by chromatography on columns QAE-Sephadex, wheat-germ agglutinin-Sepharose, hydroxyapatite Sephacryl S-200. yield C3bINA (6 mg 500ml plasma) severalfold higher than previously methods. sensitivity assay has been increased including optimal amounts 1H, it was observed essential hydrolysis C3b, whether solution bound to a cell surface. Native not hydrolysed + but haemolytically inactive form appears prolonged storage at 4 degrees C freezing thawing gives fragments alpha-chain 75000 43000 apparent mol.wt. As alpha'-chain which lost an N-terminal peptide C3a, 67000 when incubated this suggests larger fragment smaller one C-terminal. pH optimum soluble substrates 6.0, no clear classification type enzyme belongs obtained.