Purified Proteins
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Name: SC5b-9 Complex
Catalog Number: A127
Sizes Available: 100 µg/vial
Concentration: 1.0 mg/mL (see Certificate of Analysis for exact conc.)
Form: Liquid
Purity: >90% by SDS-PAGE
Buffer: 10 mM sodium phosphate, 145 mM NaCl, pH 7.3
Extinction Coeff. A280 nm = 1.03 at 1.0 mg/mL
Molecular Weight: ~1,030,000 Da (~13 chains)
Preservative: None, 0.22 µm filtered
Storage: -70oC or below. Avoid freeze/thaw.
Source:
for HBsAg and for antibodies to HCV, HIV-1 and HIV-II).
Precautions: Use normal precautions for
handling human blood products.
Origin: Manufactured in the
General Description
Vitronectin (S Protein) binds to membrane attack complexes that fail to insert into membranes. The result is a soluble complex of S Protein and C5b-9 and this has been named SC5b-9 (Dodds, A.W. and Sim, R.B. (1997)). Activation of complement in the absence of bilipid layer membranes results in most of the activated C5 forming SC5b-9 complexes. This can occur with activating particles such as immune complexes, yeast and bacterial cell walls. The SC5b-9 complexes can have more than one C9 (usually three) and more than one S Protein (usually three) per complex. Thus, the typical molecular weight is ~1,030,000 Da.
One C5b-7 complex can bind up to
three molecules of S Protein. If C8 or C8
and C9 have already bound to the C5b-7 complex three S Protein molecules will
bind to these complexes as well. The
C5b6 and C5b-7 complexes sometimes diffuse away from the target cell and enter
the membrane of a nearby cell. This is
called bystander lysis or reactive lysis and can be a significant source of
pathology. Binding of S Protein blocks
this non-specific lysis. Diffusion of
these early complexes away from the activating surface may result in addition
of C8 and C9 to the complex prior to S Protein binding. Once S Protein binds to these complexes it
prevents their membranolytic functions, thus creating
soluble complexes that are subsequently cleared from circulation.
Physical
Characteristics & Structure
The molecular weight of SC5b-9 Complex has a maximum approximate molecular weight of 1,030,000 Da and it is composed of ~13 polypeptide chains. Variations in molecular weight may occur due to the fact that SC5b-9 complexes may have 1 to 3 C9 molecules and 1 to 3 S Protein molecules per complex.
Function
See General Description above.
Assays
SC5b-9 has no functional activity. Several commercial ELISA kits specific for SC5b-9 are available. These are sold by BD Biosciences, Technoclone Ltd, Quidel, and HyCult Biotechnology. Most rely on capture of the SC5b-9 with antibodies specific for neo-antigens on the complex and secondary detection with antibodies to complement proteins of the C5b-9 complex.
Applications
See General Description above.
In vivo
The normal serum concentration of SC5b-9 is low. Normal baseline levels for properly stored plasma range from less than 100 ng/mL to 600 ng/mL SC5b-9 or less than 0.1% of maximal conversion. Elevated levels of circulating SC5b-9 complexes have been associated with bacterial infections and other diseases where complement activation is known to occur.
Regulation
SC5b-9 complexes form spontaneously and the process has no known regulators. S Protein does compete for newly formed C5b-9 with other lipid-binding molecules in plasma such as LDL and HDL. After formation SC5b-9 complexes are cleared from the circulation.
Deficiencies
Deficiencies of C5, C6, C7, C8, C9 or S Protein will prevent formation of complete SC5b-9 complexes.
Diseases
As stated above, deficiencies of C5, C6, C7, C8, C9 or S protein will prevent formation of complete SC5b-9 complexes. The inability to form MAC (C5b-9 complexes) is a serious problem due to the high susceptibility to bacterial infections. No known diseases are specifically associated with the inability to produce soluble SC5b-9 complexes.
Precautions/Toxicity/Hazards
This protein is purified from human plasma, therefore precautions appropriate for handling any blood-derived product must be used even though the source was shown by certified tests to be negative for HBsAg, HTLV-I/II, STS, and for antibodies to HCV, HIV-1 and HIV-II.
Hazard
Code: B WGK
MSDS available upon request.
References
Bauer, J., Podack, E.R. and Valet, G. (1979) Determination of the number of lytic sites in biconcave and spheroid erythrocyte ghosts after complement lysis. J. Immunol. 122:2032-2036.
Dodds, A.W. and Sim, R.B. editors (1997) Complement. A Practical Approach
(ISBN 019963539)
Law, S.K.A. and Reid, K.B.M. (1995) Complement 2nd
Edition (ISBN 0199633568)
Morgan, B.P. ed. (2000) Complement Methods
and Protocols. (ISBN
0-89603-654-5) Humana Press, Inc.,
Müller-Eberhard, H.J. (1984) The membrane attack complex. Springer Semin. Immunopathology 7:93-141.
Podack, E.R. (1984) Molecular composition of the tubular structure of the membrane attack complex of complement. J. Biol. Chem. 259: 8641-8647.
Rommel, F.A. and Mayer, M.M. (1973) Studies of guinea pig complement component C9: reaction kinetics and evidence that lysis of EAC1-8 results from a single membrane lesion caused by one molecule of C9. J. Immunol. 110:637-647.
Ross, G.D. (1986) Immunobiology of the Complement System. (ISBN 0-12-5976402) Academic Press, Orlando.
FOR
RESEARCH USE ONLY.
NOT FOR HUMAN OR DRUG
USE.
Complement
Technology, Inc.
Phone: 903-581-8284
FAX: 903-581-0491
Email: contactCTI@aol.com
Web: www.ComplementTech.com