S100B (Human) ELISA
The Human S100B ELISA is a HRP labelled antibody based sandwich enzyme immunoassay for the quantitative measurement of human S100B protein in serum, cerebrospinal fluid, heparin plasma and tissue culture medium.
S-100B is a member of highly homologous Ca2+ binding proteins family that possess two EF-hand motifs. The family of S100 proteins consists of 19 members. Most S100 proteins exist as dimers (frequently homodimers) within cells. Exclusively expressed in vertebrates, S100 is implicated in various intracellular and extracellular regulatory activities. Studies indicate that S100 proteins are involved in the inhibition of protein phosphorylation, inhibition of cytosceletal constituent assembly, regulation of Ca2+ homeostasis, stimulation of enzyme activities, and interaction with transcription factors. S100B is abundant in the nervous system where it is predominantly expressed in astrocytes, oligodendrocytes and Schwann cells. When secreted by astrocytes, S100B has neurotrophic effects during development and nerve regeneration at physiologic (nanomolar) concentrations. However high (micromolar) concentrations of S100B have shown to be neurotoxic, participating in the physiology of neurodegenerative disorders. The clinical values have been demonstrated in stroke, cerebral complications association with cardiac arrest and in patients with severe as well as minor head injury. Patients with progressive melanoma disease also show elevated serum concentrations of S100B.
In the Human S100B ELISA, calibrators, quality controls and samples are incubated with polyclonal anti-cow S100B antibody coated in microtitration wells. After 90 minutes incubation and washing, monoclonal anti-human S100B antibody labelled with horseradish peroxidase (HRP) is added to the wells and incubated with captured S100B. After 90 minutes incubation and another washing step, the remaining conjugate is allowed to react with the substrate tetramethylbenzidine and H2O2. The reaction is stopped by addition of acidic solution and absorbance of the resulting yellow colour product is measured spectrophotometrically at 450 nm. The absorbance is proportional to the concentration of S100B. A standard curve is constructed by plotting absorbance values versus S100B concentrations of calibrators and concentrations of unknown samples are determined using this standard curve.
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