1tus
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(New page: 200px<br /><applet load="1tus" size="450" color="white" frame="true" align="right" spinBox="true" caption="1tus" /> '''SOLUTION STRUCTURE OF REACTIVE-SITE HYDROLYZ...)
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Revision as of 01:29, 21 November 2007
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SOLUTION STRUCTURE OF REACTIVE-SITE HYDROLYZED TURKEY OVOMUCOID THIRD DOMAIN BY NUCLEAR MAGNETIC RESONANCE AND DISTANCE GEOMETRY METHODS
Overview
The solution structure of reactive-site hydrolyzed turkey ovomucoid third, domain (OMTKY3*) was determined by n.m.r. methods. A total of 655 distance, constraints was applied in a distance geometry/simulated annealing, approach to calculate a family of structures consistent with the n.m.r., data. The input data included 24 torsion angle constraints, 14 hydrogen, bonds, 611 constraints derived from two-dimensional nuclear Overhauser, enhancement spectroscopy data, and three disulfide bridges. Stereospecific, assignments were included for the hydrogens of 26 beta-methylene groups, and for seven isopropyl methyl groups (46% chiral assignments). OMTKY3* in, solution retains the global fold and overall secondary structure of the, intact inhibitor (OMTKY3) but exhibits local structural differences at and, adjacent to the clip site. In particular, the hydrogen-bonding network, observed at the reactive-site of the intact inhibitor is disrupted, and, the position of Tyr20 is altered in the modified inhibitor. No evidence, was found for ion pairing between the oppositely charged termini at the, clip site. Surprisingly, in light of numerous changes indicating that, OMTKY3* is less stable than OMTKY3, rotation of the Tyr31 ring was found, to be slow in OMTKY3* at 30 degrees C. In OMTKY3, slow rotation of the, Tyr31 ring was observed only at temperatures below 15 degrees C. The, n.m.r. structures of OMTKY3* are compared here with the similarly, calculated structures of OMTKY3. This represents the first comparison of, an intact and modified (reactive-site clipped) proteinase inhibitor under, identical conditions. On comparison with published X-ray structures of, modified avian ovomucoid third domains from two other species, the present, structure of OMTKY3* in solution was found to resemble that of the, Japanese quail protein (OMJPQ3*) more closely than that of the more, closely homologous silver pheasant protein (OMSVP3*).
About this Structure
1TUS is a Single protein structure of sequence from Meleagris gallopavo. Full crystallographic information is available from OCA.
Reference
Solution structure of reactive-site hydrolyzed turkey ovomucoid third domain by nuclear magnetic resonance and distance geometry methods., Walkenhorst WF, Krezel AM, Rhyu GI, Markley JL, J Mol Biol. 1994 Sep 23;242(3):215-30. PMID:8089843
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