| Description | PurityNo C4 detectable by hemolytic assayPrecautionsUse normal precautions for handling animal blood productsGeneral DescriptionC4-deficient guinea pigs were characterized in 1971 as being completely genetically and functionally deficient in C4 (Ellman, L. et al. (1970); Ellman, L. et al. (1971); PurityNo C4 detectable by hemolytic assayPrecautionsUse normal precautions for handling animal blood productsGeneral DescriptionC4-deficient guinea pigs were characterized in 1971 as being completely genetically and functionally deficient in C4 (Ellman, L. et al. (1970); Ellman, L. et al. (1971); Frank, M.M., et al. (1971)). This line of guinea pigs has been maintained and used extensively for the characterization of complement. In fact, these animals were a key element in the rediscovery and detailed characterization of the alternative pathway of complement (Ellman, L. et al. (1971); Frank, M.M., et al. (1971)). The product is tested for the absence of C4 by functional assays for classical pathway activity. C4-D guinea pig serum reconstituted with human C4 is certified to possess a functional classical pathway for complement activation after reconstitution (Morgan, B.P. (2000); Dodds, A.W. and Sim, R.B. (1997)). The absence of C4 would also be predicted to prevent complement activation by the lectin pathway, but the function of this pathway is not tested.Physical CharacteristicsC4-D guinea pig serum is supplied as a clear, straw-colored liquid containing all proteins of normal guinea pig serum except complement component C4.FunctionThe depleted serum is tested for remaining classical pathway activity by hemolytic assays using antibody-sensitized sheep erythrocytes. The depleted serum is reconstituted with human C4 and retested to verify that a functional classical and alternative pathways are restored. The Certificate of Analysis provided with each lot gives a description of the assays and specific titers for the depleted and reconstituted sera compared to normal human serum. Assays The unit of classical pathway activity is the CH50. A similar unit, the C4H50, is used to quantitate the activity of C4 and C4-D guinea pig serum. A C4H50 unit is the amount of functional C4 needed to lyse 50% of 3 x107 EA cells (antibody-sensitized sheep erythrocytes) when that amount of C4 is incubated with the recommended volume of C4-D guinea pig serum in GVB++ in a total volume of 500 µL for 30 min at 37℃. This amount of C4i ndicates the sensitivity of the assay for C4 which is typically less than 2 ng C4 with 10µL C4-D guinea pig serum. See the Certificate of Analysis for lot specific values.ApplicationsC4-D guinea pig serum is used to assay C4 activity in samples and to supply a serum unable to activate complement via the classical pathway. Note that C1 and C2 may still be activated in the absence of C4, but whereas there is a C2 by-pass system there does not appear to be an efficient C4 by-pass mechanism. Low level lysis of EA in C4-D guinea pig serum has been shown to require activation of the early classical and the alternative pathways (Wagner, E. et al. (1999)).Precautions/Toxicity/HazardsThe source is human serum, 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 and for antibodies to HCV, HIV-1 and HIV-II.Hazard Code: B WGK Germany 3MSDS is available upon request... Read More | Inquire | Inquire | Reverse transcriptases are enzymes encoded in retroviruses viral genome. The enzyme is responsible for transcription of the viral RNA to produce a dsDNA that can be inserted into the host genome.Reverse transcriptases are multifunctional enzymes. These enzymes exhibit an RNA and DNA directed Reverse transcriptases are enzymes encoded in retroviruses viral genome. The enzyme is responsible for transcription of the viral RNA to produce a dsDNA that can be inserted into the host genome.Reverse transcriptases are multifunctional enzymes. These enzymes exhibit an RNA and DNA directed polymerase activity. In addition reverse transcriptases catalyze the degradation of RNA in an RNA-DNA hybrid. The exonucleolytic activity proceeds in a 5' ---> 3' direction. The RNA or DNA directed activity requires a template (RNA or DNA) and a primer. The following is a schematic illustration of the reaction:Unit definition: One unit incorporates 1 nanomole of tritiated dTMP into acid insoluble productsusing poly(A)•oligo(dT) 12-18 as the template-primer in 20 minutes at 37° C.ApplicationsHIV reverse transcriptase is used for research on the AIDS primer. However it can be substituted for AMV reverse transcriptase, which is mainly used to transcribe mRNA into double stranded cDNA, that can be inserted into prokaryotic vectors. The enzyme can also be used with either single stranded DNA or RNA templates to make probes for use in hybridization experiments. It can be used for labeling the termini of DNA fragments with protruding 5' termini. The enzyme can also be used to sequence DNAs by the dideoxy chain termination method of Sanger when the Klenow fragment of E. coli DNA polymerase I, or the T7 DNA polymerase yield unsatisfactory results.Reagents0.05 M Tris, pH 8.3, containing 0.008 M MgCl21 mg/ml polyadenylic acid in water (poly A)DNA primer:Oligo d(T)12-181 µ mole dTTP/mL stock solution[methyl-3H]-Thymidine 5'-triphosphate (3H-dTTP)dTTP-3H-dTTP working mix: Add 1-2 µL 3H-dTTP per mL of 100 nmol/mL dTTP in order to obtain 1 to 1.5 x 105 cpm/mL1% bovine serum albumin10% perchloric acid1% perchloric acidBuffer substrate reaction mixture: Prepare fresh, immediately before use:For each 1mL of reaction mixture required mix:0.7 mL Tris/HCl, pH 8.3, 0.008M MgCl20.3 mL 1 mg/mL poly(A) RNA template0.005 mL 0.02 mg/mL oligo d(T)12-18 DNA primer0.02mL 1% BSAEnzymedilute as needed wtih 0.05M Tris/HCl, pH 8.3, 0.008M MgCl2 containing 0.1 mg/mL (1%) BSAProcedurePipette into each tube as follows:Buffer substrate mix：0.1 mLdTTP-3H3-dTTP：0.1 mLEnzyme：5-10 µLIncubate 20 minutes at 37° C. Stop reaction by adding 1 ml 10% cold perchloric acid. Filter through 0.2µ manifold filters used with Millipore vacuum manifold. Wash four times using 2mL 1% cold perchloric acid/wash. Transfer filter to scintillation vials. Add 2mL Cellosolve (or 2-methoxyethanol) to dissolve filter. Filters become opaque upon addition of Cellosolve. Make sure filters are dissolved before proceeding. Add 10mL scintillation cocktail and count.Calculation... 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 |