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| - | [[Image:1nm5.jpg|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1nm5| PDB=1nm5 | SCENE= }} | | {{STRUCTURE_1nm5| PDB=1nm5 | SCENE= }} |
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| - | '''R. rubrum transhydrogenase (dI.Q132N)2(dIII)1 asymmetric complex'''
| + | ===R. rubrum transhydrogenase (dI.Q132N)2(dIII)1 asymmetric complex=== |
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| - | ==Overview==
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| - | Transhydrogenase, found in bacterial membranes and inner mitochondrial membranes of animal cells, couples the redox reaction between NAD(H) and NADP(H) to proton translocation. In this work, the invariant Gln132 in the NAD(H)-binding component (dI) of the Rhodospirillum rubrum transhydrogenase was substituted with Asn (to give dI.Q132N). Mixtures of the mutant protein and the NADP(H)-binding component (dIII) of the enzyme readily produced an asymmetric complex, (dI.Q132N)(2)dIII(1). The X-ray structure of the complex revealed specific changes in the interaction between bound nicotinamide nucleotides and the protein at the hydride transfer site. The first-order rate constant of the redox reaction between nucleotides bound to (dI.Q132N)(2)dIII(1) was <1% of that for the wild-type complex, and the deuterium isotope effect was significantly decreased. The nucleotide binding properties of the dI component in the complex were asymmetrically affected by the Gln-to-Asn mutation. In intact, membrane-bound transhydrogenase, the substitution completely abolished all catalytic activity. The results suggest that Gln132 in the wild-type enzyme behaves as a "tether" or a "tie" in the mutual positioning of the (dihydro)nicotinamide rings of NAD(H) and NADP(H) for hydride transfer during the conformational changes that are coupled to the translocation of protons across the membrane. This ensures that hydride transfer is properly gated and does not take place in the absence of proton translocation.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_12564924}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 12564924 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_12564924}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Asymmetric complex]] | | [[Category: Asymmetric complex]] |
| | [[Category: Rossman domain]] | | [[Category: Rossman domain]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 02:41:51 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 06:39:38 2008'' |
Revision as of 03:39, 28 July 2008
Template:STRUCTURE 1nm5
R. rubrum transhydrogenase (dI.Q132N)2(dIII)1 asymmetric complex
Template:ABSTRACT PUBMED 12564924
About this Structure
1NM5 is a Protein complex structure of sequences from Rhodospirillum rubrum. Full crystallographic information is available from OCA.
Reference
Glutamine 132 in the NAD(H)-binding component of proton-translocating transhydrogenase tethers the nucleotides before hydride transfer., van Boxel GI, Quirk PG, Cotton NP, White SA, Jackson JB, Biochemistry. 2003 Feb 11;42(5):1217-26. PMID:12564924
Page seeded by OCA on Mon Jul 28 06:39:38 2008
