Biogenesis of Novel Quinone Coenzymes

摘要: Recently, two novel quinonoid coenzymes, 2,4,5-trihydroxyphenylalanine quinone (topa quinone; TPQ) and tryptophan tryptophylquinone (TTQ), were identified in copper-containing amine oxidase methylamine dehydrogenase, respectively. Unlike the formerly known coenzyme, pyrroloquinoline (PQQ), which is non-covalently bound to several prokaryotic dehydrogenases produced through its own biosynthetic pathway, each of TPQ TTQ covalently polypeptide chain as an integral amino acid residue encoded by a codon for normal (unmodified) gene. Thus, these coenzymes must be generated post-translational modification precursor acid; TPQ, oxidation specific tyrosine occurring consensus Asn-Tyr-Asp/Glu sequence, TTQ, cross-linking with another separated 50 residues same chain. We recently demonstrated that, using inactive forms bacterial copper oxidases, self-processing protein participation ions. On other hand, absence prosthetic metal ion dehydrogenase well existence periplasm renders biogenesis more complicated, likely requiring external enzymatic system(s).