Back to Search Start Over

Functional characterization of human C3/cobra venom factor hybrid proteins for therapeutic complement depletion.

Authors :
Fritzinger DC
Hew BE
Thorne M
Pangburn MK
Janssen BJ
Gros P
Vogel CW
Source :
Developmental and comparative immunology [Dev Comp Immunol] 2009; Vol. 33 (1), pp. 105-16.
Publication Year :
2009

Abstract

Cobra venom factor (CVF) is a structural and functional analog of complement C3 isolated from cobra venom. Both CVF and C3b can bind factor B and subsequently form the bimolecular C3/C5 convertases CVF,Bb or C3b,Bb, respectively. The two homologous enzymes exhibit several differences of which the difference in physico-chemical stability is most important, allowing continuous activation of C3 and C5 by CVF,Bb, leading to serum complement depletion. Here we describe the detailed functional properties of two hybrid proteins in which the 113 or 315 C-terminal residues of C3 were replaced with corresponding CVF sequences. Both hybrid proteins formed stable convertases that exhibited C3-cleaving activity, although at different rates. Neither convertase cleaved C5. Both convertases showed partial resistance to inactivation by factors H and I, allowing them to deplete complement in human serum. These data demonstrate that functionally important structural differences between CVF and C3 are located in the very C-terminal region of both homologous proteins, and that small substitutions in human C3 with homologous CVF sequence result in C3 derivatives with CVF-like functions. Such hybrid proteins are important tools to study the structure/function relationships in both C3 and CVF, and these "humanized CVF" proteins may become reagents for therapeutic complement depletion.

Details

Language :
English
ISSN :
0145-305X
Volume :
33
Issue :
1
Database :
MEDLINE
Journal :
Developmental and comparative immunology
Publication Type :
Academic Journal
Accession number :
18760301
Full Text :
https://doi.org/10.1016/j.dci.2008.07.006