1tg2

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spinqualitylabelsall models 1tg2, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of phenylalanine hydroxylase A313T mutant with 7,8-dihydrobiopterin bound

Contents 1 Overview 2 Disease 3 About this Structure 4 Reference

Overview

Phenylketonuria patients harboring a subset of phenylalanine hydroxylase, (PAH) mutations have recently shown normalization of blood phenylalanine, levels upon oral administration of the PAH cofactor tetrahydrobiopterin, [(6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4)]. Several hypotheses, have been put forward to explain BH4 responsiveness, but the molecular, basis for the corrective effect(s) of BH4 has not been understood. We have, investigated the biochemical, kinetic, and structural changes associated, with BH4-responsive mutations (F39L, I65T, R68S, H170D, E178G, V190A, R261Q, A300S, L308F, A313T, A373T, V388M, E390G, P407S, and Y414C). The, biochemical and kinetic characterization of the 15 mutants studied points, toward a multifactorial basis for the BH4 responsiveness; the mutants show, residual activity (>30% of WT) and display various kinetic defects, including increased Km (BH4) and reduced cooperativity of substrate, binding, but no decoupling of cofactor (BH4) oxidation. For some, BH4, seems to function through stabilization and protection of the enzyme from, inactivation and proteolytic degradation. In the crystal structures of a, phenylketonuria mutant, A313T, minor changes were seen when compared with, the WT PAH structures, consistent with the mild effects the mutant has, upon activity of the enzyme both in vitro and in vivo. Truncations made in, the A313T mutant PAH form revealed that the N and C termini of the enzyme, influence active site binding. Of fundamental importance is the, observation that BH4 appears to increase Phe catabolism if at least one of, the two heterozygous mutations has any residual activity remaining.

Disease

Known diseases associated with this structure: Hyperphenylalaninemia, mild OMIM:[261600], Phenylketonuria OMIM:[261600]

About this Structure

1TG2 is a Single protein structure of sequence from Homo sapiens with FE and H2B as ligands. Active as Phenylalanine 4-monooxygenase, with EC number 1.14.16.1 Full crystallographic information is available from OCA.

Reference

Correction of kinetic and stability defects by tetrahydrobiopterin in phenylketonuria patients with certain phenylalanine hydroxylase mutations., Erlandsen H, Pey AL, Gamez A, Perez B, Desviat LR, Aguado C, Koch R, Surendran S, Tyring S, Matalon R, Scriver CR, Ugarte M, Martinez A, Stevens RC, Proc Natl Acad Sci U S A. 2004 Nov 30;101(48):16903-8. Epub 2004 Nov 19. PMID:15557004

Page seeded by OCA on Mon Nov 12 19:24:26 2007