C8 Human
Human Plasma.
Sterile filtered solution.
Greater than 95% as determined by SDS-PAGE.
Description
Human Complement C8 produced in Human plasma is glycosylated polypeptide chain conteining 3 chains and having a total molecular mass of 151kDa.
Product Specs
Human Complement C8 is a glycosylated protein comprising three polypeptide chains: alpha, beta, and gamma. The alpha and gamma chains are linked by a disulfide bond, while the beta chain associates non-covalently with the alpha-gamma complex. This protein plays a crucial role in the formation of the membrane attack complex (MAC), a critical component of the complement system's immune response. C8 is activated upon binding to C5b-C6-C7 complexes that have assembled on the target cell membrane. The complement activation pathway generates proteolytic enzyme complexes that bind to the target surface. These enzymes cleave the larger alpha chain of C5, releasing C5a and activating C5b. While unstable, C5b remains bound to the activating complex briefly, during which it can bind to a single C6 molecule from the surrounding fluid; otherwise, it decays and loses its MAC-forming ability. The C5b-6 complex can remain attached to the C3/C5 convertase. Subsequently, the binding of a single C7 molecule exposes a membrane-binding region, enabling the C5b-6-7 complex to insert into the target cell's lipid bilayer. Each C5b-7 complex then binds to one molecule of C8, anchoring the complex firmly within the membrane.
Human Complement C8, derived from human plasma, is a glycosylated polypeptide comprised of three chains, with a combined molecular weight of 151kDa.
Sterile-filtered liquid solution.
The C8 protein solution is prepared in phosphate-buffered saline (PBS) at pH 7.2.
Human C8 remains stable for 2-4 weeks when stored at 4°C, provided the entire vial is used within that period. For extended storage, freeze the product below -20°C. Adding a carrier protein (0.1% HSA or BSA) is recommended for long-term storage. Avoid repeated freeze-thaw cycles to maintain protein integrity.
The purity of this product is determined to be greater than 95% using SDS-PAGE analysis.
Each plasma donation undergoes rigorous testing to ensure the absence of antibodies against HIV-1, HIV-2, HCV, and HBsAg.
Human Plasma.
Product Science Overview
Complement Component 8 is a heterotrimer composed of three different polypeptide chains: C8 alpha (C8A), C8 beta (C8B), and C8 gamma (C8G). These chains are encoded by separate genes located on different chromosomes. The C8A and C8B chains are located on chromosome 1, while the C8G chain is located on chromosome 9 .
- C8A: This chain is involved in binding to the target cell membrane.
- C8B: This chain is crucial for the interaction with other complement components.
- C8G: This chain stabilizes the complex and aids in its proper function.
The three chains are held together by noncovalent bonds, forming a stable complex that can interact with other components of the complement system .
The primary function of C8 is to participate in the formation of the membrane attack complex (MAC). The MAC is a multi-protein complex that forms pores in the cell membranes of pathogens, leading to cell lysis and death. The formation of the MAC involves several steps:
- Activation: The complement system is activated through one of three pathways: the classical pathway, the lectin pathway, or the alternative pathway.
- Assembly: Complement components C5b, C6, and C7 sequentially bind to form a complex that attaches to the target cell membrane.
- Insertion: C8 binds to the C5b-C6-C7 complex and inserts into the cell membrane.
- Completion: Multiple C9 molecules bind to the C5b-C6-C7-C8 complex, forming a pore in the membrane.
The insertion of C8 into the membrane is a critical step in the formation of the MAC, as it facilitates the binding of C9 and the subsequent formation of the pore .
A deficiency in Complement Component 8 can lead to increased susceptibility to certain bacterial infections, particularly those caused by Neisseria species, such as meningitis and gonorrhea . There are two main types of C8 deficiency:
- Type I Deficiency: This type is characterized by the absence of the C8 beta chain, resulting in a non-functional C8 complex.
- Type II Deficiency: This type involves a dysfunctional C8 molecule that lacks the C8 alpha-gamma subunit.
Patients with C8 deficiency may present with recurrent bacterial infections and require medical intervention to manage their condition .
Research on Complement Component 8 has provided valuable insights into the mechanisms of immune response and the development of therapeutic interventions. Understanding the structure and function of C8 has implications for the treatment of immune-related disorders and the design of complement-based therapies.
