Allosteric effect of tetrahydrobiopterin cofactors on tyrosine hydroxylase activity.
Allostery of tyrosine hydroxylase was found by kinetical studies of partially purified tyrosine hydroxylase from clonal rat pheochromocytoma PC12h cells. Positive cooperativity toward the cofactors, (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin [(6R)BH4] and (6S)-L-erythro-5,6,7,8-tetrahydrobiopterin [(6S)BH4], was observed. It is indicated that biopterin might be the regulatory factor of the enzyme polymers, which changes the affinity for the cofactor itself. Moreover, the stereochemical structure of (6R)BH4, the naturally-occurring cofactor, took an important role on the kinetical properties of the enzyme in concern with L-tyrosine.
Department of Neurology, Nagoya University School of Medicine, Japan.
M
M
Minami
T
T
Takahashi
W
W
Maruyama
A
A
Takahashi
T
T
Nagatsu
M
M
Naoi
D000494:Allosteric Regulation; D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives* / Q000494:pharmacology; D007700:Kinetics; D046911:Macromolecular Substances; D011487:Protein Conformation; D051381:Rats; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000302:isolation & purification / Q000378:metabolism*
D046911:Macromolecular Substances; D001708:Biopterins; D014443:Tyrosine; D014446:Tyrosine 3-Monooxygenase; C003402:sapropterin