Purification of C1 inhibitor. A new approach for the isolation of this biologically important plasma protease inhibitor.


Journal Article

C1 inhibitor (C1-INH) acts to inhibit active enzymes of both the classical complement and Hageman factor-dependent pathways. Previously reported C1-INH purification procedures were multistep and most have been associated with significant loss in specific functional activity. We have developed a simple chromatographic procedure which yields a pure C1-INH protein from normal human plasma with a specific activity equal to or greater than the starting sample. Briefly, protease inhibitor-treated, pooled human citrated plasma was fractionated with polyethylene glycol (PEG 4000); the supernatant fraction that remained soluble at 16% was obtained. The inhibitor was precipitated with 45% PEG. The resulting precipitate was solubilized and chromatographed on DEAE Sephacel using a linear salt gradient. The eluted fractions containing the C1-INH and other contaminants were pooled and dialyzed against the starting buffer of the next chromatographic step. A unique separation procedure using zinc ion chelate-coupled agarose was employed as the second chromatographic step. The eluted C1-INH, after zinc ion chromatography, displayed a significant enhancement in purity and maintained a specific functional activity twice that of plasma. The final procedure utilized immunoadsorption chromatography using an anti-contaminant column. Under reducing conditions on sodium dodecyl sulfate polyacrylamide gel electrophoresis, the purified C1-INH migrated as a single band with an apparent molecular weight of 90,000-105,000, but under non-reducing conditions, a doublet with apparent molecular weights of 94,000-100,000 and 85,000-93,000 was seen. C1-INH antigenic concentrations were measured and shown to be correlated in serum, citrate plasma, and EDTA plasma from 16 normal subjects.

Full Text

Cited Authors

  • Prograis, LJ; Hammer, CH; Katusha, K; Frank, MM

Published Date

  • May 4, 1987

Published In

Volume / Issue

  • 99 / 1

Start / End Page

  • 113 - 122

PubMed ID

  • 3553333

Pubmed Central ID

  • 3553333

International Standard Serial Number (ISSN)

  • 0022-1759

Digital Object Identifier (DOI)

  • 10.1016/0022-1759(87)90039-1


  • eng

Conference Location

  • Netherlands