6rsa
From Proteopedia
(New page: 200px<br /><applet load="6rsa" size="450" color="white" frame="true" align="right" spinBox="true" caption="6rsa, resolution 2.0Å" /> '''NUCLEAR MAGNETIC RESO...) |
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caption="6rsa, resolution 2.0Å" /> | caption="6rsa, resolution 2.0Å" /> | ||
'''NUCLEAR MAGNETIC RESONANCE AND NEUTRON DIFFRACTION STUDIES OF THE COMPLEX OF RIBONUCLEASE*A WITH URIDINE VANADATE, A TRANSITION-STATE ANALOGUE'''<br /> | '''NUCLEAR MAGNETIC RESONANCE AND NEUTRON DIFFRACTION STUDIES OF THE COMPLEX OF RIBONUCLEASE*A WITH URIDINE VANADATE, A TRANSITION-STATE ANALOGUE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The complex of ribonuclease A (RNase A) with uridine vanadate (U-V), a | + | The complex of ribonuclease A (RNase A) with uridine vanadate (U-V), a transition-state analogue, has been studied with 51V and proton NMR spectroscopy in solution and by neutron diffraction in the crystalline state. Upon the addition of aliquots of U-V at pH 6.6, the C epsilon-H resonances of the two active-site histidine residues 119 and 12 decrease in intensity while four new resonances appear. Above pH 8 and below pH 5, these four resonances decrease in intensity as the complex dissociates. These four resonances are assigned to His-119 and His-12 in protonated and unprotonated forms in the RNase-U-V complex. These resonances do not titrate or change in relative area in the pH range 5-8, indicating a slow protonation process, and the extent of protonation remains constant with ca. 58% of His-12 and ca. 26% of His-119 being protonated. The results of diffraction studies show that both His-12 and His-119 occupy well-defined positions in the RNase-U-V complex and that both are protonated. However, while the classic interpretation of the mechanism of action of RNase based on the proposal of Findlay et al. [Findlay, D., Herries, D. G., Mathias, A. P., Rabin, B. R., & Ross, C. A. (1962) Biochem. J. 85, 152-153] requires both His-12 and His-119 to be in axial positions relative to the pentacoordinate transition state, in the diffraction structure His-12 is found to be in an equatorial position, while Lys-41 is close to an axial position. Hydrogen exchange data show that the mobility and accessibility of amides in the RNase-U-V complex do not significantly differ from what was observed in the native enzyme. The results of both proton NMR in solution and neutron diffraction in the crystal are compared and interpreted in terms of the mechanism of action of RNase. |
==About this Structure== | ==About this Structure== | ||
| - | 6RSA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with UVC and DOD as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Pancreatic_ribonuclease Pancreatic ribonuclease], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.5 3.1.27.5] Full crystallographic information is available from [http:// | + | 6RSA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with <scene name='pdbligand=UVC:'>UVC</scene> and <scene name='pdbligand=DOD:'>DOD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Pancreatic_ribonuclease Pancreatic ribonuclease], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.5 3.1.27.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6RSA OCA]. |
==Reference== | ==Reference== | ||
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[[Category: rna)]] | [[Category: rna)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:16:43 2008'' |
Revision as of 17:16, 21 February 2008
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NUCLEAR MAGNETIC RESONANCE AND NEUTRON DIFFRACTION STUDIES OF THE COMPLEX OF RIBONUCLEASE*A WITH URIDINE VANADATE, A TRANSITION-STATE ANALOGUE
Overview
The complex of ribonuclease A (RNase A) with uridine vanadate (U-V), a transition-state analogue, has been studied with 51V and proton NMR spectroscopy in solution and by neutron diffraction in the crystalline state. Upon the addition of aliquots of U-V at pH 6.6, the C epsilon-H resonances of the two active-site histidine residues 119 and 12 decrease in intensity while four new resonances appear. Above pH 8 and below pH 5, these four resonances decrease in intensity as the complex dissociates. These four resonances are assigned to His-119 and His-12 in protonated and unprotonated forms in the RNase-U-V complex. These resonances do not titrate or change in relative area in the pH range 5-8, indicating a slow protonation process, and the extent of protonation remains constant with ca. 58% of His-12 and ca. 26% of His-119 being protonated. The results of diffraction studies show that both His-12 and His-119 occupy well-defined positions in the RNase-U-V complex and that both are protonated. However, while the classic interpretation of the mechanism of action of RNase based on the proposal of Findlay et al. [Findlay, D., Herries, D. G., Mathias, A. P., Rabin, B. R., & Ross, C. A. (1962) Biochem. J. 85, 152-153] requires both His-12 and His-119 to be in axial positions relative to the pentacoordinate transition state, in the diffraction structure His-12 is found to be in an equatorial position, while Lys-41 is close to an axial position. Hydrogen exchange data show that the mobility and accessibility of amides in the RNase-U-V complex do not significantly differ from what was observed in the native enzyme. The results of both proton NMR in solution and neutron diffraction in the crystal are compared and interpreted in terms of the mechanism of action of RNase.
About this Structure
6RSA is a Single protein structure of sequence from Bos taurus with and as ligands. Active as Pancreatic ribonuclease, with EC number 3.1.27.5 Full crystallographic information is available from OCA.
Reference
Nuclear magnetic resonance and neutron diffraction studies of the complex of ribonuclease A with uridine vanadate, a transition-state analogue., Borah B, Chen CW, Egan W, Miller M, Wlodawer A, Cohen JS, Biochemistry. 1985 Apr 9;24(8):2058-67. PMID:4016100
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