Biopterin is a coenzyme that is produced within the body.

It is an oxidized degradation product of tetrahydrobiopterin

Tetrahydrobiopterin

Tetrahydrobiopterin or sapropterin 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 , melatonin, dopamine, norepinephrine ,...

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Defects in biopterin synthesis or regeneration can cause a form of hyperphenylalaninemia (a disease with symptoms similar to PKU

Phenylketonuria

Phenylketonuria is an autosomal recessive metabolic genetic disorder characterized by a mutation in the gene for the hepatic enzyme phenylalanine hydroxylase , rendering it nonfunctional. This enzyme is necessary to metabolize the amino acid phenylalanine to the amino acid tyrosine...

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Biopterin is synthesized in several parts of the body, including the pineal gland.

Biopterin deficiency has been associated with a variety of disorders, including dystonia

Dystonia

Dystonia is a neurological movement disorder, in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning or reaction to...

  and rabies

Rabies

Rabies is a viral disease that causes acute encephalitis in warm-blooded animals. It is zoonotic , most commonly by a bite from an infected animal. For a human, rabies is almost invariably fatal if post-exposure prophylaxis is not administered prior to the onset of severe symptoms...

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