1n65
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(New page: 200px<br /><applet load="1n65" size="450" color="white" frame="true" align="right" spinBox="true" caption="1n65" /> '''FAMILY OF NMR SOLUTION STRUCTURES OF CA CE C...)
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Revision as of 19:52, 20 November 2007
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FAMILY OF NMR SOLUTION STRUCTURES OF CA CE CALBINDIN D9K IN DENATURATING CONDITIONS
Overview
Early steps of unfolding of P43M Calbindin D(9k) have been evaluated by, NMR spectroscopy on the native dicalcium and on the paramagnetic, monocerium-substituted derivative. Although at 2 M GdmHCl the protein core, maintains its overall folding and structure, amide (15)N R(2) measurements, and cross correlation rates between N-H dipole-dipole relaxation and (15)N, CSA relaxation reveal a closer and stronger packing of the hydrophobic, interactions in the protein as a response to the presence of denaturing, agents in solution. A complete reorientation of the Met43 side chain, toward the hydrophobic core is accomplished by the disappearance of the, millisecond dynamics observed on the native form of Calbindin D(9k), while, cross correlation rates provide evidence that the two-way hydrogen bond, between Leu23 and Val61 is broken or substantially weakened. The, substitution of the calcium ion in site II with the paramagnetic Ce(3+), ion allowed us to obtain a number of long-range nonconventional, constraints, namely, pseudocontact shifts, which were used, together with, the NOEs collected on the native state, to monitor subtle structural, variations occurring in the non-native state of the protein. Although the, average rmsd between the structures of native and non-native states is, small (0.48 A), structural rearrangements could be reliably identified., Our results provide unprecedented information about the behavior of, Calbindin D(9k) during the early steps of unfolding. Furthermore, they, constitute strong evidence of the efficiency of paramagnetism-based, constraints in monitoring subtle structural changes that are beyond the, sensitivity of an approach based only on NOE.
About this Structure
1N65 is a Single protein structure of sequence from Bos taurus with CE as ligand. Full crystallographic information is available from OCA.
Reference
Monitoring the early steps of unfolding of dicalcium and mono-Ce3+-substituted forms of P43M calbindin D9k., Jimenez B, Poggi L, Piccioli M, Biochemistry. 2003 Nov 11;42(44):13066-73. PMID:14596622
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