A homogeneous fluorescent immunoassay for human immunoglobulin M

Autor:	D Worah, F E Ward, K K Yeung, R J Carrico
Rok vydání:	1981
Předmět:	Chromatography biology Chemistry Biochemistry (medical) Clinical Biochemistry Acetal medicine.disease_cause Fluorescence Molecular biology Hydrolysis chemistry.chemical_compound Covalent bond Homogeneous biology.protein medicine Moiety Antibody Escherichia coli
Zdroj:	Clinical Chemistry. 27:673-677
ISSN:	1530-8561 0009-9147
DOI:	10.1093/clinchem/27.5.673
Popis:	We describe a homogeneous substrate-labeled fluorescent immunoassay for human IgM. In this competitive-binding method we use a fluorogenic substrate for Escherichia coli beta-galactosidase, N-(6-aminohexyl)-7-beta-galactosyl-coumarin-3-carboxamide, which is covalently coupled to IgM. The fluorescence emission intensity of the labeled IgM at 450 nm (with excitation at 400 nm) is negligible, but when beta-galactosidase is added, the acetal linkage of the galactosyl moiety is hydrolyzed and the product has a greatly enhanced fluorescence. Formation of this fluorescent product is inhibited when antibody specific for IgM is bound to the labeled protein. In competitive-binding reactions, IgM from the serum competes with the labeled IgM for antibody binding sites and consequently the fluorescence produced by the enzymic reaction is related to the IgM concentration. The working range of the assay is between 0.5 and 5.0 g of IgM per liter when a 50-fold predilution of the sera is used. The assay does not cross react significantly with immunoglobulins G or A.
Databáze:	OpenAIRE
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