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| {{STRUCTURE_1di4| PDB=1di4 | SCENE= }} | | {{STRUCTURE_1di4| PDB=1di4 | SCENE= }} |
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| '''ROLE OF AMINO ACID RESIDUES AT TURNS IN THE CONFORMATIONAL STABILITY AND FOLDING OF HUMAN LYSOZYME'''
| | ===ROLE OF AMINO ACID RESIDUES AT TURNS IN THE CONFORMATIONAL STABILITY AND FOLDING OF HUMAN LYSOZYME=== |
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| ==Overview==
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| To clarify the role of amino acid residues at turns in the conformational stability and folding of a globular protein, six mutant human lysozymes deleted or substituted at turn structures were investigated by calorimetry, GuHCl denaturation experiments, and X-ray crystal analysis. The thermodynamic properties of the mutant and wild-type human lysozymes were compared and discussed on the basis of their three-dimensional structures. For the deletion mutants, Delta47-48 and Delta101, the deleted residues are in turns on the surface and are absent in human alpha-lactalbumin, which is homologous to human lysozyme in amino acid sequence and tertiary structure. The stability of both mutants would be expected to increase due to a decrease in conformational entropy in the denatured state; however, both proteins were destabilized. The destabilizations were mainly caused by the disappearance of intramolecular hydrogen bonds. Each part deleted was recovered by the turn region like the alpha-lactalbumin structure, but there were differences in the main-chain conformation of the turn between each deletion mutant and alpha-lactalbumin even if the loop length was the same. For the point mutants, R50G, Q58G, H78G, and G37Q, the main-chain conformations of these substitution residues located in turns adopt a left-handed helical region in the wild-type structure. It is thought that the left-handed non-Gly residue has unfavorable conformational energy compared to the left-handed Gly residue. Q58G was stabilized, but the others had little effect on the stability. The structural analysis revealed that the turns could rearrange the main-chain conformation to accommodate the left-handed non-Gly residues. The present results indicate that turn structures are able to change their main-chain conformations, depending upon the side-chain features of amino acid residues on the turns. Furthermore, stopped-flow GuHCl denaturation experiments on the six mutants were performed. The effects of mutations on unfolding-refolding kinetics were significantly different among the mutant proteins. The deletion/substitutions in turns located in the alpha-domain of human lysozyme affected the refolding rate, indicating the contribution of turn structures to the folding of a globular protein.
| | The line below this paragraph, {{ABSTRACT_PUBMED_10913274}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 10913274 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_10913274}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Stability]] | | [[Category: Stability]] |
| [[Category: Turn]] | | [[Category: Turn]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:52:14 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 23:05:37 2008'' |
