1c1x
From Proteopedia
(New page: 200px<br /><applet load="1c1x" size="450" color="white" frame="true" align="right" spinBox="true" caption="1c1x, resolution 1.40Å" /> '''L-PHENYLALANINE DEHY...) |
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| - | [[Image:1c1x.jpg|left|200px]]<br /><applet load="1c1x" size=" | + | [[Image:1c1x.jpg|left|200px]]<br /><applet load="1c1x" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1c1x, resolution 1.40Å" /> | caption="1c1x, resolution 1.40Å" /> | ||
'''L-PHENYLALANINE DEHYDROGENASE STRUCTURE IN TERNARY COMPLEX WITH NAD+ AND L-3-PHENYLLACTATE'''<br /> | '''L-PHENYLALANINE DEHYDROGENASE STRUCTURE IN TERNARY COMPLEX WITH NAD+ AND L-3-PHENYLLACTATE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Phenylalanine dehydrogenase catalyzes the reversible, pyridine | + | Phenylalanine dehydrogenase catalyzes the reversible, pyridine nucleotide-dependent oxidative deamination of L-phenylalanine to form phenylpyruvate and ammonia. We have characterized the steady-state kinetic behavior of the enzyme from Rhodococcus sp. M4 and determined the X-ray crystal structures of the recombinant enzyme in the complexes, E.NADH.L-phenylalanine and E.NAD(+). L-3-phenyllactate, to 1.25 and 1.4 A resolution, respectively. Initial velocity, product inhibition, and dead-end inhibition studies indicate the kinetic mechanism is ordered, with NAD(+) binding prior to phenylalanine and the products' being released in the order of ammonia, phenylpyruvate, and NADH. The enzyme shows no activity with NADPH or other 2'-phosphorylated pyridine nucleotides but has broad activity with NADH analogues. Our initial structural analyses of the E.NAD(+).phenylpyruvate and E.NAD(+). 3-phenylpropionate complexes established that Lys78 and Asp118 function as the catalytic residues in the active site [Vanhooke et al. (1999) Biochemistry 38, 2326-2339]. We have studied the ionization behavior of these residues in steady-state turnover and use these findings in conjunction with the structural data described both here and in our first report to modify our previously proposed mechanism for the enzymatic reaction. The structural characterizations also illuminate the mechanism of the redox specificity that precludes alpha-amino acid dehydrogenases from functioning as alpha-hydroxy acid dehydrogenases. |
==About this Structure== | ==About this Structure== | ||
| - | 1C1X is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodococcus_sp. Rhodococcus sp.] with K, NA, PO4, HFA, NAD and IPA as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1C1X is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodococcus_sp. Rhodococcus sp.] with <scene name='pdbligand=K:'>K</scene>, <scene name='pdbligand=NA:'>NA</scene>, <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=HFA:'>HFA</scene>, <scene name='pdbligand=NAD:'>NAD</scene> and <scene name='pdbligand=IPA:'>IPA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1C1X OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Rhodococcus sp.]] | [[Category: Rhodococcus sp.]] | ||
| - | [[Category: Thoden, J | + | [[Category: Thoden, J B.]] |
| - | [[Category: Vanhooke, J | + | [[Category: Vanhooke, J L.]] |
[[Category: HFA]] | [[Category: HFA]] | ||
[[Category: IPA]] | [[Category: IPA]] | ||
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[[Category: oxidoreductase]] | [[Category: oxidoreductase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:01:30 2008'' |
Revision as of 10:01, 21 February 2008
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L-PHENYLALANINE DEHYDROGENASE STRUCTURE IN TERNARY COMPLEX WITH NAD+ AND L-3-PHENYLLACTATE
Overview
Phenylalanine dehydrogenase catalyzes the reversible, pyridine nucleotide-dependent oxidative deamination of L-phenylalanine to form phenylpyruvate and ammonia. We have characterized the steady-state kinetic behavior of the enzyme from Rhodococcus sp. M4 and determined the X-ray crystal structures of the recombinant enzyme in the complexes, E.NADH.L-phenylalanine and E.NAD(+). L-3-phenyllactate, to 1.25 and 1.4 A resolution, respectively. Initial velocity, product inhibition, and dead-end inhibition studies indicate the kinetic mechanism is ordered, with NAD(+) binding prior to phenylalanine and the products' being released in the order of ammonia, phenylpyruvate, and NADH. The enzyme shows no activity with NADPH or other 2'-phosphorylated pyridine nucleotides but has broad activity with NADH analogues. Our initial structural analyses of the E.NAD(+).phenylpyruvate and E.NAD(+). 3-phenylpropionate complexes established that Lys78 and Asp118 function as the catalytic residues in the active site [Vanhooke et al. (1999) Biochemistry 38, 2326-2339]. We have studied the ionization behavior of these residues in steady-state turnover and use these findings in conjunction with the structural data described both here and in our first report to modify our previously proposed mechanism for the enzymatic reaction. The structural characterizations also illuminate the mechanism of the redox specificity that precludes alpha-amino acid dehydrogenases from functioning as alpha-hydroxy acid dehydrogenases.
About this Structure
1C1X is a Protein complex structure of sequences from Rhodococcus sp. with , , , , and as ligands. Full crystallographic information is available from OCA.
Reference
Rhodococcus L-phenylalanine dehydrogenase: kinetics, mechanism, and structural basis for catalytic specificity., Brunhuber NM, Thoden JB, Blanchard JS, Vanhooke JL, Biochemistry. 2000 Aug 8;39(31):9174-87. PMID:10924111
Page seeded by OCA on Thu Feb 21 12:01:30 2008
Categories: Protein complex | Rhodococcus sp. | Thoden, J B. | Vanhooke, J L. | HFA | IPA | K | NA | NAD | PO4 | Amino acid dehydrogenase | Oxidative deamination mechanism | Oxidoreductase
