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CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V99A MUTANT
Structural highlights
DiseaseLYSC_HUMAN Defects in LYZ are a cause of amyloidosis type 8 (AMYL8) [MIM:105200; also known as systemic non-neuropathic amyloidosis or Ostertag-type amyloidosis. AMYL8 is a hereditary generalized amyloidosis due to deposition of apolipoprotein A1, fibrinogen and lysozyme amyloids. Viscera are particularly affected. There is no involvement of the nervous system. Clinical features include renal amyloidosis resulting in nephrotic syndrome, arterial hypertension, hepatosplenomegaly, cholestasis, petechial skin rash.[1] FunctionLYSC_HUMAN Lysozymes have primarily a bacteriolytic function; those in tissues and body fluids are associated with the monocyte-macrophage system and enhance the activity of immunoagents. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTo clarify the contribution of the hydrophobic effect to the conformational stability of human lysozyme, a series of Val to Ala mutants were constructed. The thermodynamic parameters for the denaturation of these nine mutant proteins were determined using differential scanning calorimetry (DSC), and the crystal structures were solved at high resolution. The denaturation Gibbs energy (delta delta G) and enthalpy (delta delta H) values of the mutant proteins ranged from +2.2 to- 6.3 kJ/mol and from +7 to -17 kJ/mol, respectively. The structural analyses showed that the mutation site and/or the residues around it in some proteins shifted toward the created cavity, and the substitutions affected not only the mutations site but also other parts far from the site, although the structural changes were not as great. Correlation between the changes in the thermodynamic parameters and the structural features of mutant proteins was examined, including the five Ile to Val mutant human lysozymes [Takano et al. (1995) J. Mol. Biol. 254, 62-76]. There was no simple general correlation between delta delta G and the changes in hydrophobic surface area exposed upon denaturation (delta delta ASAHP). We found only a new correlation between the delta delta G and delta delta ASAHP of all of the hydrophobic residues if the effect of the secondary structure propensity was taken into account. Contribution of the hydrophobic effect to the stability of human lysozyme: calorimetric studies and X-ray structural analyses of the nine valine to alanine mutants.,Takano K, Yamagata Y, Fujii S, Yutani K Biochemistry. 1997 Jan 28;36(4):688-98. PMID:9020766[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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