Description
Principle of the Assay: This assay employs the competitive enzyme immunoassay technique. The microtiter plate provided in this kit has been pre-coated with an antibody specific to BH4. Standards or samples are then added to the appropriate microtiter plate wells with a Horseradish Peroxidase (HRP)-conjugated BH4 and incubated. The competitive inhibition reaction is launched between with HRP labeled BH4 and unlabeled BH4 with the antibody. A substrate solution is added to the wells and the color develops in opposite to the amount of BH4 in the sample. The color development is stopped and the intensity of the color is measured.
Background: Tetrahydrobiopterin (BH4, THB, trade name Kuvan) or sapropterin (INN) is a naturally occurring essential cofactor of the three aromatic amino acid hydroxylase enzymes, used in the degradation of amino acid phenylalanine and in the biosynthesis of the neurotransmitters serotonin (5-hydroxytryptamine, 5-HT), melatonin, dopamine, norepinephrine (noradrenaline), epinephrine (adre naline), and is a cofactor for the production of nitric oxide (NO) by the nitric oxide synthases. Tetrahydrobiopterin was discovered to play a role as an enzymatic cofactor. The first enzyme found to use tetrahydrobiopterin is phenylalanine hydroxylase (PAH). Tetrahydrobiopterin is biosynthesized from guanosine triphosphate (GTP) by three chemical reactions mediated by the enzymes GTP cyclohydrolase I (GTPCH),6-pyruvoyltetrahydropterin synthase (PTPS), and sepiapterin reductase (SR)