1kw0
From Proteopedia
(New page: 200px<br /> <applet load="1kw0" size="450" color="white" frame="true" align="right" spinBox="true" caption="1kw0, resolution 2.50Å" /> '''Catalytic Domain of...) |
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caption="1kw0, resolution 2.50Å" /> | caption="1kw0, resolution 2.50Å" /> | ||
'''Catalytic Domain of Human Phenylalanine Hydroxylase (Fe(II)) in Complex with Tetrahydrobiopterin and Thienylalanine'''<br /> | '''Catalytic Domain of Human Phenylalanine Hydroxylase (Fe(II)) in Complex with Tetrahydrobiopterin and Thienylalanine'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Phenylalanine hydroxylase catalyzes the stereospecific hydroxylation of | + | Phenylalanine hydroxylase catalyzes the stereospecific hydroxylation of L-phenylalanine, the committed step in the degradation of this amino acid. We have solved the crystal structure of the ternary complex (hPheOH-Fe(II).BH(4).THA) of the catalytically active Fe(II) form of a truncated form (DeltaN1-102/DeltaC428-452) of human phenylalanine hydroxylase (hPheOH), using the catalytically active reduced cofactor 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)) and 3-(2-thienyl)-L-alanine (THA) as a substrate analogue. The analogue is bound in the second coordination sphere of the catalytic iron atom with the thiophene ring stacking against the imidazole group of His285 (average interplanar distance 3.8A) and with a network of hydrogen bonds and hydrophobic contacts. Binding of the analogue to the binary complex hPheOH-Fe(II).BH(4) triggers structural changes throughout the entire molecule, which adopts a slightly more compact structure. The largest change occurs in the loop region comprising residues 131-155, where the maximum r.m.s. displacement (9.6A) is at Tyr138. This loop is refolded, bringing the hydroxyl oxygen atom of Tyr138 18.5A closer to the iron atom and into the active site. The iron geometry is highly distorted square pyramidal, and Glu330 adopts a conformation different from that observed in the hPheOH-Fe(II).BH(4) structure, with bidentate iron coordination. BH(4) binds in the second coordination sphere of the catalytic iron atom, and is displaced 2.6A in the direction of Glu286 and the iron atom, relative to the hPheOH-Fe(II).BH(4) structure, thus changing its hydrogen bonding network. The active-site structure of the ternary complex gives new insight into the substrate specificity of the enzyme, notably the low affinity for L-tyrosine. Furthermore, the structure has implications both for the catalytic mechanism and the molecular basis for the activation of the full-length tetrameric enzyme by its substrate. The large conformational change, moving Tyr138 from a surface position into the active site, may reflect a possible functional role for this residue. |
==Disease== | ==Disease== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1KW0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with FE2, H4B and TIH as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Phenylalanine_4-monooxygenase Phenylalanine 4-monooxygenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.14.16.1 1.14.16.1] Full crystallographic information is available from [http:// | + | 1KW0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=FE2:'>FE2</scene>, <scene name='pdbligand=H4B:'>H4B</scene> and <scene name='pdbligand=TIH:'>TIH</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Phenylalanine_4-monooxygenase Phenylalanine 4-monooxygenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.14.16.1 1.14.16.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KW0 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Phenylalanine 4-monooxygenase]] | [[Category: Phenylalanine 4-monooxygenase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Andersen, O | + | [[Category: Andersen, O A.]] |
[[Category: Flatmark, T.]] | [[Category: Flatmark, T.]] | ||
[[Category: Hough, E.]] | [[Category: Hough, E.]] | ||
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[[Category: ferrous iron]] | [[Category: ferrous iron]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:38:30 2008'' |
Revision as of 11:38, 21 February 2008
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Catalytic Domain of Human Phenylalanine Hydroxylase (Fe(II)) in Complex with Tetrahydrobiopterin and Thienylalanine
Contents |
Overview
Phenylalanine hydroxylase catalyzes the stereospecific hydroxylation of L-phenylalanine, the committed step in the degradation of this amino acid. We have solved the crystal structure of the ternary complex (hPheOH-Fe(II).BH(4).THA) of the catalytically active Fe(II) form of a truncated form (DeltaN1-102/DeltaC428-452) of human phenylalanine hydroxylase (hPheOH), using the catalytically active reduced cofactor 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)) and 3-(2-thienyl)-L-alanine (THA) as a substrate analogue. The analogue is bound in the second coordination sphere of the catalytic iron atom with the thiophene ring stacking against the imidazole group of His285 (average interplanar distance 3.8A) and with a network of hydrogen bonds and hydrophobic contacts. Binding of the analogue to the binary complex hPheOH-Fe(II).BH(4) triggers structural changes throughout the entire molecule, which adopts a slightly more compact structure. The largest change occurs in the loop region comprising residues 131-155, where the maximum r.m.s. displacement (9.6A) is at Tyr138. This loop is refolded, bringing the hydroxyl oxygen atom of Tyr138 18.5A closer to the iron atom and into the active site. The iron geometry is highly distorted square pyramidal, and Glu330 adopts a conformation different from that observed in the hPheOH-Fe(II).BH(4) structure, with bidentate iron coordination. BH(4) binds in the second coordination sphere of the catalytic iron atom, and is displaced 2.6A in the direction of Glu286 and the iron atom, relative to the hPheOH-Fe(II).BH(4) structure, thus changing its hydrogen bonding network. The active-site structure of the ternary complex gives new insight into the substrate specificity of the enzyme, notably the low affinity for L-tyrosine. Furthermore, the structure has implications both for the catalytic mechanism and the molecular basis for the activation of the full-length tetrameric enzyme by its substrate. The large conformational change, moving Tyr138 from a surface position into the active site, may reflect a possible functional role for this residue.
Disease
Known diseases associated with this structure: Hyperphenylalaninemia, mild OMIM:[261600], Phenylketonuria OMIM:[261600]
About this Structure
1KW0 is a Single protein structure of sequence from Homo sapiens with , and as ligands. Active as Phenylalanine 4-monooxygenase, with EC number 1.14.16.1 Full crystallographic information is available from OCA.
Reference
Crystal structure of the ternary complex of the catalytic domain of human phenylalanine hydroxylase with tetrahydrobiopterin and 3-(2-thienyl)-L-alanine, and its implications for the mechanism of catalysis and substrate activation., Andersen OA, Flatmark T, Hough E, J Mol Biol. 2002 Jul 26;320(5):1095-108. PMID:12126628
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