1dv9: Difference between revisions
New page: left|200px<br /><applet load="1dv9" size="450" color="white" frame="true" align="right" spinBox="true" caption="1dv9" /> '''STRUCTURAL CHANGES ACCOMPANYING PH-INDUCED D... |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:1dv9.gif|left|200px]]<br /><applet load="1dv9" size=" | [[Image:1dv9.gif|left|200px]]<br /><applet load="1dv9" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1dv9" /> | caption="1dv9" /> | ||
'''STRUCTURAL CHANGES ACCOMPANYING PH-INDUCED DISSOCIATION OF THE B-LACTOGLOBULIN DIMER'''<br /> | '''STRUCTURAL CHANGES ACCOMPANYING PH-INDUCED DISSOCIATION OF THE B-LACTOGLOBULIN DIMER'''<br /> | ||
==Overview== | ==Overview== | ||
We have used NMR spectroscopy to determine the three-dimensional (3D) | We have used NMR spectroscopy to determine the three-dimensional (3D) structure, and to characterize the backbone dynamics, of a recombinant version of bovine beta-lactoglobulin (variant A) at pH 2. 6, where the protein is a monomer. The structure of this low-pH form of beta-lactoglobulin is very similar to that of a subunit within the dimer at pH 6.2. The root-mean-square deviation from the pH 6.2 (crystal) structure, calculated for backbone atoms of residues 6-160, is approximately 1.3 A. Differences arise from the orientation, with respect to the calyx, of the A-B and C-D loops, and of the flanking three-turn alpha-helix. The hydrophobic cavity within the calyx is retained at low pH. The E-F loop (residues 85-90), which moves to occlude the opening of the cavity over the pH range 7.2-6.2, is in the "closed" position at pH 2.6, and the side chain of Glu89 is buried. We also carried out measurements of (15)N T(1)s and T(2)s and (1)H-(15)N heteronuclear NOEs at pH 2.6 and 37 degrees C. Although the residues of the E-F loop (residues 86-89) have the highest crystallographic B-factors, the conformation of this loop is reasonably well defined by the NMR data, and its backbone is not especially mobile on the pico- to nanosecond time scale. Several residues (Ser21, Lys60, Ala67, Leu87, and Glu112) exhibit large ratios of T(1) to T(2), consistent with conformational exchange on a micro- to millisecond time scale. The positions of these residues in the 3D structure of beta-lactoglobulin are consistent with a role in modulating access to the hydrophobic cavity. | ||
==About this Structure== | ==About this Structure== | ||
1DV9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus]. Full crystallographic information is available from [http:// | 1DV9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DV9 OCA]. | ||
==Reference== | ==Reference== | ||
| Line 13: | Line 13: | ||
[[Category: Bos taurus]] | [[Category: Bos taurus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Barlow, P | [[Category: Barlow, P N.]] | ||
[[Category: Jameson, G | [[Category: Jameson, G B.]] | ||
[[Category: Sawyer, L.]] | [[Category: Sawyer, L.]] | ||
[[Category: Smith, M | [[Category: Smith, M H.]] | ||
[[Category: Uhrin, D.]] | [[Category: Uhrin, D.]] | ||
[[Category: Uhrinova, S.]] | [[Category: Uhrinova, S.]] | ||
| Line 24: | Line 24: | ||
[[Category: triple resonance experiments]] | [[Category: triple resonance experiments]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:20:48 2008'' | ||
Revision as of 13:20, 21 February 2008
|
STRUCTURAL CHANGES ACCOMPANYING PH-INDUCED DISSOCIATION OF THE B-LACTOGLOBULIN DIMER
OverviewOverview
We have used NMR spectroscopy to determine the three-dimensional (3D) structure, and to characterize the backbone dynamics, of a recombinant version of bovine beta-lactoglobulin (variant A) at pH 2. 6, where the protein is a monomer. The structure of this low-pH form of beta-lactoglobulin is very similar to that of a subunit within the dimer at pH 6.2. The root-mean-square deviation from the pH 6.2 (crystal) structure, calculated for backbone atoms of residues 6-160, is approximately 1.3 A. Differences arise from the orientation, with respect to the calyx, of the A-B and C-D loops, and of the flanking three-turn alpha-helix. The hydrophobic cavity within the calyx is retained at low pH. The E-F loop (residues 85-90), which moves to occlude the opening of the cavity over the pH range 7.2-6.2, is in the "closed" position at pH 2.6, and the side chain of Glu89 is buried. We also carried out measurements of (15)N T(1)s and T(2)s and (1)H-(15)N heteronuclear NOEs at pH 2.6 and 37 degrees C. Although the residues of the E-F loop (residues 86-89) have the highest crystallographic B-factors, the conformation of this loop is reasonably well defined by the NMR data, and its backbone is not especially mobile on the pico- to nanosecond time scale. Several residues (Ser21, Lys60, Ala67, Leu87, and Glu112) exhibit large ratios of T(1) to T(2), consistent with conformational exchange on a micro- to millisecond time scale. The positions of these residues in the 3D structure of beta-lactoglobulin are consistent with a role in modulating access to the hydrophobic cavity.
About this StructureAbout this Structure
1DV9 is a Single protein structure of sequence from Bos taurus. Full crystallographic information is available from OCA.
ReferenceReference
Structural changes accompanying pH-induced dissociation of the beta-lactoglobulin dimer., Uhrinova S, Smith MH, Jameson GB, Uhrin D, Sawyer L, Barlow PN, Biochemistry. 2000 Apr 4;39(13):3565-74. PMID:10736155
Page seeded by OCA on Thu Feb 21 12:20:48 2008