| Description | Biochemical Test:Electrophoresis (purity > 80%) | Protein Purity>95% by SDS-PAGEExtinction Coeff.A276 nm = 0.456 at 1.0 mg/mLMolecular Weight8,759 Da (single chain)General DescriptionNatural human C4a is prepared by cleavage of human C4 protein by human C1s. It is produced during activation of both the classical and lectin pathways of complementProtein Purity>95% by SDS-PAGEExtinction Coeff.A276 nm = 0.456 at 1.0 mg/mLMolecular Weight8,759 Da (single chain)General DescriptionNatural human C4a is prepared by cleavage of human C4 protein by human C1s. It is produced during activation of both the classical and lectin pathways of complement. C4a is a member of the anaphylatoxin family of three proteins (C3a, C4a and C5a) produced by the activation of complement (Hugli, T.E. et al. (1981)). It is an unglycosylated polypeptidecontaining 77 amino acids with a molecular mass of 8,759 daltons. Many of the biological functions of C4a are similar to those of C3a, but the specific activities are far below those of C3a. C4a activity is so low, in fact, that it was initially thought to be inactive. These measured activities include inducing muscle contraction in the guinea pig ileum test (spasmogenic activity), desensitization of muscle to C3a stimulation suggesting that the same receptor for both C3a and C4a is involved (tachyphylactic activity) and inducing vascular permeability in human skin (Gorski J.P. et al. (1979)). C4a does not show tachyphylactic activity against C5a or chemotactic activity. Removal of the C-terminal arginine by serum carboxypeptidase N destroys all these activities (Meuller-Ortiz, S.L., et al. (2009)). C4a appears to act through the C3a receptor (C3aR) which is a G-protein coupled receptor found widely distributed on peripheral tissues, lymphoid cells (neutrohphils, monocyes, and eosinophils) and in the central nervous system (astrocytes, neurons and glial cells) (Law, S.K.A. and Reid, K.B.M. (1995)). Physical Characteristics & StructureMolecular weight: 8,759 calculated molecular mass. Observed mass (MALDI-TOF) is 8,762 + 9 mass units. pI = 9.0 to 9.5 (Gorski, J.P. et al. (1981))Amino acid sequence (77 amino acids): NVNFQKAINE KLGQYASPTA KRCCQDGVTR LPMMRSCEQR AARVQQPDCR EPFLSCCQFA ESLRKKSRDK GQAGLQRC4a is thought to be structurally very similar to C3a and C5a to which it is homologous. Thus its 3D structure is probably similar to the X-ray-derived crystal structureof C3a (Huber, R. et al. (1980)) and the NMR derived structure of C3a: Nettesheim, D.G. et al. (1988); Murray, I. et al. (1999).FunctionSee General Description above. C4a exhibits much weaker biological activities than C3a and C5a. Its activity in inducing erythema and edema in human skin is 25,000-fold weaker than that of C5a and 100-fold weaker than C3a per nanomole. The spasmogenic activity of C4a is 2000-fold weaker than C5a and 100-fold weaker than that of C3a. Due to these differences the role of C4a in these responses in vivo is thought to be negligible.AssaysTwo well established assays for C4a and C3a functional activities include induction of contraction in the guinea pig ileum and the permeation of a dye such as trypan blue from the vasculature into skin. The anaphylatoxins also induce mast cell degranulation, (measured as histamine release), platelet aggregation, IL-1 release from monocytes and the release of prostaglandins and leukotrienes from many cells and tissues. The other assays used for C3a (Dodds, A.W. and Sim, R.B. (1997)) should also respond to C4a, but few reports have described utilizing these assays with C4a. ELISA kits for the assay of C4a levels (or more correctly C4a desArg levels) in blood and other fluids are sold by several companies. These measurements are useful for detecting complement activation in vivo, but the interpretation of their meaning is complicated by the fact that clearance of the anaphylatoxins is rapid. In vivoFreshly drawn normal human serum contains significant levels of all three anaphylatoxins. Although these may represent the resting concentration in vivo it is difficult to draw or store blood without some complement activation so a true in vivo concentration is difficult to determine. The presence of EDTA and Futhan in the collection tubes can minimize this background (Pfeifer, P.H. et al. (1999)). Full activation of all C4 in blood (600µg/mL) would result in ~3,400 nM C4a (~30 µg/mL). Due to the low biological activity of C4a it could require activation of most of the C4 in a small region to achieve the micromolar C4a concentrations necessary to elicit a response.RegulationC4a levels are regulated by three processes: formation, inactivation and clearance. There are two enzymes that cleave C4 and release C4a: C1s and MASP-2. C4a is “inactivated” by removal of its C-terminal arginine amino acid. The product C4a desArg (or C4a without the C-terminal arginine) is produced by the action of the plasma enzyme carboxypeptidase N (Mueller-Ortiz S.L. et al. (2009)). The inactivation is rapid and most C4a is converted to C4a desArg within minutes of its formation. Inactivated C4a lack measurable biological activity. Because of the large number of cells bearing C3a/C4areceptors (endothelial, immune, smooth muscle, neuronal, etc.) the capture, internalization and digestion of C4a and C4a desArg probably results in its removal from circulation.DeficienciesA deficiency of C4 or a deficiency of all of the enzymes that cleave C4 to generate C4a could result in the absence of C4a. There are no known complete deficiencies of all ofthe C4 cleaving enzymes. Examples of C4 deficient humans and mice exist (Wessels, M.R. et al. (1995)), but the degree to which pathologies associated with C4 deficiency are due to the lack of C4 or the absence of C4a is unclear. DiseasesThere are no known diseases connected to C4a or C4a desArg. Precautions/Toxicity/HazardsThe source of C4a is human serum, therefore appropriate precautions must be observed 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.Injection can cause anaphylatic shock which is a generalized circulatory collapse similar to that caused by an allergic reaction.Hazard Code: B WGK Germany 3... Read More | Parathyroid Hormone (1-34), human, biotinylated is a probe for the parathyroid hormone receptor, can be used for analyzing the interaction between parathyroid hormone and parathyroid hormone receptors in living cells and for purifying hormone-receptor comAppearance:SolidBiological Activity:Parathyroid Hormone (1-34), human, biotinylated is a probe for the parathyroid hormone receptor, can be used for analyzing the interaction between parathyroid hormone and parathyroid hormone receptors in living cells and for purifying hormone-receptor comAppearance:SolidBiological Activity:Parathyroid Hormone (1-34), human, biotinylated is a probe for the parathyroid hormone receptor, can be used for analyzing the interaction between parathyroid hormone and parathyroid hormone receptors in living cells and for purifying hormone-receptor com... Read More | Purity: >90%, by SDS-PAGE visualized with Coomassie® Blue Staining.Description：Involved in the high-affinity maltose membrane transport system MalEFGK. Initial receptor for the active transport of and chemotaxis toward maltooligosaccharides.Epitope tagging offers an easy and universalPurity: >90%, by SDS-PAGE visualized with Coomassie® Blue Staining.Description：Involved in the high-affinity maltose membrane transport system MalEFGK. Initial receptor for the active transport of and chemotaxis toward maltooligosaccharides.Epitope tagging offers an easy and universal strategy for the identification and purification of proteins derived by recombinant DNA technology. The insertion of a Maltose Binding Protein (MBP) tag creates a stable fusion product that does not interfere with the bioactivity of the protein or with the biodistribution of the MBP tagged product... Read More | Purity:>95%, by SDS-PAGE visualized with Coomassie® Blue Staining. Description： 100B, previously called S100 beta, belongs to the S100 family within the EF-hand superfamily of Ca2+ binding proteins. S100 proteins contain two EF-hand motifs that differ in affinity, separated by a hingePurity:>95%, by SDS-PAGE visualized with Coomassie® Blue Staining. Description： 100B, previously called S100 beta, belongs to the S100 family within the EF-hand superfamily of Ca2+ binding proteins. S100 proteins contain two EF-hand motifs that differ in affinity, separated by a hinge region with a hydrophobic cleft that is exposed upon Ca2+ binding. S100B is a 91 amino acid (aa) protein, after removal of the initial methionine, and is found as homodimers of 10.4 kDa monomers. Human S100B shares 99%, 98%, 100%, 99% and 97% aa sequence identity with mouse, rat, rabbit, equine and bovine S100B, respectively. Within the S100 family, human S100B shows the highest aa identity (59%) with S100A1. S100B is expressed primarily by astrocytes and oligodendrocytes in the central nervous system, and by Schwann cells in the peripheral nervous system. Ca2+-bound S100B interacts in vitro with at least 20 cytoplasmic proteins, including several structural molecules such as tubulin and GFAP. It can inhibit the phosphorylation of these kinase substrates and others such as tau and neuromodulin. Astrocytes can secrete S100B, which then acts in a cytokine-like manner. Nanomolar concentrations of S100B are secreted constitutively, promote proliferation, and are neurotrophic and anti-apoptotic. Blood levels of S100B reflect extracellular concentrations within the nervous system, and are elevated in Down’s syndrome, Alzheimer’s disease and Tourette’s syndrome, metabolic stress, acute brain injury and brain tumors. Micromolar concentrations of S100B can be destructive and pro-apoptotic; they induce the expression of iNOS, COX-2, IL-1, IL‑6 and TNF-alpha by microglia, astrocytes or neurons. Most extracellular actions of S100B can be mediated by RAGE (receptor for advanced glycation end products), which is also a receptor for other S100 proteins... Read More |