1ujp
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(New page: 200px<br /><applet load="1ujp" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ujp, resolution 1.34Å" /> '''Crystal Structure of...)
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Revision as of 02:03, 21 November 2007
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Crystal Structure of Tryptophan Synthase A-Subunit From Thermus thermophilus HB8
Overview
In order to elucidate the thermo-stabilization mechanism of the tryptophan, synthase alpha-subunit from the extreme thermophile Thermus thermophilus, HB8 (Tt-alpha-subunit), its crystal structure was determined and its, stability was examined using DSC. The results were compared to those of, other orthologs from mesophilic and hyperthermophilic organisms. The, denaturation temperature of the Tt-alpha-subunit was higher than that of, the alpha-subunit from S. typhimurium (St-alpha-subunit) but lower than, that of the alpha-subunit from P. furiosus (Pf-alpha-subunit). Specific, denaturation enthalpy and specific denaturation heat capacity values of, the Tt-alpha-subunit were the lowest among the three proteins, suggesting, that entropy effects are responsible for the stabilization of the, Tt-alpha-subunit. Based on a structural comparison with the, St-alpha-subunit, two deletions in loop regions, an increase in the number, of ion pairs and a decrease in cavity volume seem to be responsible for, the stabilization of the Tt-alpha-subunit. The results of structural, comparison suggest that the native structure of the Tt-alpha-subunit is, better adapted to an ideally stable structure than that of the, St-alpha-subunit, but worse than that of the Pf-alpha-subunit. The results, of calorimetry suggest that the residual structure of the Tt-alpha-subunit, in the denatured state contributes to the stabilization.
About this Structure
1UJP is a Single protein structure of sequence from Thermus thermophilus with CIT as ligand. Active as Tryptophan synthase, with EC number 4.2.1.20 Full crystallographic information is available from OCA.
Reference
Stabilization mechanism of the tryptophan synthase alpha-subunit from Thermus thermophilus HB8: X-ray crystallographic analysis and calorimetry., Asada Y, Sawano M, Ogasahara K, Nakamura J, Ota M, Kuroishi C, Sugahara M, Yutani K, Kunishima N, J Biochem (Tokyo). 2005 Oct;138(4):343-53. PMID:16272128
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