Molecular weight of poly(C9). 12 to 18 C9 molecules form the transmembrane channel of complement.

Details

Serval ID
serval:BIB_6991BF520501
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Molecular weight of poly(C9). 12 to 18 C9 molecules form the transmembrane channel of complement.
Journal
Journal of Biological Chemistry
Author(s)
Tschopp J., Engel A., Podack E.R.
ISSN
0021-9258
Publication state
Published
Issued date
02/1984
Peer-reviewed
Oui
Volume
259
Number
3
Pages
1922-1928
Language
english
Abstract
Poly(C9), the tubular 27 S complex forming the transmembrane channel of the membrane attack complex of complement, was purified to homogeneity by gel filtration and sucrose density gradient ultracentrifugation. The molecular weight of poly(C9) was determined by two independent methods in addition to sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. First, sedimentation equilibrium analysis using 0.2% SDS or 1% deoxycholate containing buffer as solvents yielded a point weight average molecular weight exclusive of bound detergent of 0.9 to 1.3 X 10(6) and a weight average molecular weight of all poly(C9) complexes of 1,050,000 +/- 40,000 (S.D.). SDS and deoxycholate binding to poly(C9) was measured in an air-driven ultracentrifuge and was determined to be 0.53 +/- 0.065 (S.D.) g of SDS and 0.26 +/- 0.015 (S.D.) g of deoxycholate/g of poly(C9), respectively. Second, the mass of 27 S poly(C9) devoid of bound detergent was determined by electron scattering of unstained specimens in the scanning transmission electron microscope. The molecular weight obtained by this method was 1,078,000 +/- 194,000. The inner diameter of poly(C9) tubules imaged in top view projections by negative staining electron microscopy varied between 9 and 12 mm. The accumulated data suggest a true heterogeneity of the molecular weight of poly(C9) due to polymers with varying protomer numbers. Using a mean value of 73,500 for the molecular weight of monomeric C9, the protomer number of poly(C9) tubules appear to vary between 12 and 18 C9 subunits. Approximately 50-75% of the tubules have 14 to 16 subunits as deduced from the mass distribution determined by electron scattering and from ring size measurements. It is suggested that poly(C9) tubules with various protomer numbers may arise due to limited flexibility in the C9-C9 interaction.
Keywords
Complement C9, Ion Channels/analysis, Macromolecular Substances, Microscopy, Electron, Microscopy, Electron, Scanning, Molecular Weight, Sodium Dodecyl Sulfate
Pubmed
Web of science
Create date
24/01/2008 16:18
Last modification date
20/08/2019 15:24
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