Tryptophan tryptophylquinone
Tryptophan tryptophylquinone (TTQ) is an enzyme cofactor, generated by posttranslational modification of amino acids within the protein. Methylamine dehydrogenase (MADH), an amine dehydrogenase, requires TTQ for its catalytic function. See also
 Amicyanin

References

Alpha-Amino acids
Amino acid derivatives
Tryptamines
Indolequinones