Oligomeric domain structure of human complement factor H by X-ray and neutron solution scattering
- Royal Free Hospital School of Medicine, London (England)
- Univ. of Oxford (England)
Factor H is a regulatory component of the complement system. It has a monomer M{sub r} of 150,000. Primary structure analysis shows that the polypeptide is divided into 20 homologous regions, each 60 amino acid residues long. These are independently folding domains and are termed short consensus repeats (SCRs) or complement control protein (CCP) repeats. High-flux synchrotron x-ray and neutron scatteriing studies were performed in order to define its solution structure in conditions close to physiological. The M{sub r} of factor H was determined as 250,000-320,000 to show that factor H is dimeric. The radius of gyration R{sub G} of native factor H by X-rays or by neutrons in 0% or 100% {sup 2}H{sub 2}O buffers is not measurable but is greater than 12.5 nm. Two cross-sectional radii of gyration R{sub XS-1} and R{sub XS-2} were determined as 3.0-3.1 and 1.8 nm, respectively. Analyses of the cross-sectional intensities show that factor H is composed of two distinct subunits. This model corresponds to an actual R{sub G} fo 21-23 nm. The separation between each SCR/CCP in factor H is close to 4 nm. In the solution structure of factor H, the SCR/CCP domains are in a highly extended conformation.
- OSTI ID:
- 5076058
- Journal Information:
- Biochemistry; (United States), Vol. 30:11; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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COMPLEMENT
MOLECULAR STRUCTURE
BIOLOGICAL PATHWAYS
HEAVY WATER
NEUTRON DIFFRACTION
PH VALUE
SCATTERING
SYNCHROTRON RADIATION
X-RAY DIFFRACTION
BREMSSTRAHLUNG
COHERENT SCATTERING
DIFFRACTION
ELECTROMAGNETIC RADIATION
HYDROGEN COMPOUNDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PROTEINS
RADIATIONS
WATER
550602* - Medicine- External Radiation in Diagnostics- (1980-)