1lz4
ENTHALPIC DESTABILIZATION OF A MUTANT HUMAN LYSOZYME LACKING A DISULFIDE BRIDGE BETWEEN CYSTEINE-77 AND CYSTEINE-95
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OverviewOverview
To understand the role of disulfide bridges in protein stability, the, thermodynamic changes in the denaturation of two mutant human lysozymes, lacking a disulfide bridge between Cys-77 and Cys-95 (C77A and C77/95A), were analyzed using differential scanning calorimetry (DSC). At pH 3.0 and, 57 degrees C, the stabilities of both the C77A and C77/95A mutants were, decreased about 4.6 kcal.mol-1 in Gibbs free energy change. Under the same, conditions, the enthalpy changes (delta H) were 94.8 and 90.8 kcal.mol-1, respectively, which were smaller than that of the wild type (100.8, kcal.mol-1). The destabilization of the mutants was caused by enthalpic, factors. Although X-ray crystallography indicated that the mutants, preserve the wild-type tertiary structure, removal of the disulfide bridge, increased the flexibility of the native state of the mutants. This was, indicated both by an increase in the crystallographic thermal factors, (B-factors) and by a decrease in the affinity of N-acetylglucosamine, trimer [(NAG)3] observed using isothermal titration calorimetry (DTC) due, to entropic effects. Thus, the effect of cross-linking on the stability of, a protein is not solely explained by the entropy change in denaturation.
DiseaseDisease
Known diseases associated with this structure: Amyloidosis, renal OMIM:[153450], Microphthalmia, syndromic 1 OMIM:[309800]
About this StructureAbout this Structure
1LZ4 is a Single protein structure of sequence from Homo sapiens. Active as Lysozyme, with EC number 3.2.1.17 Full crystallographic information is available from OCA.
ReferenceReference
Enthalpic destabilization of a mutant human lysozyme lacking a disulfide bridge between cysteine-77 and cysteine-95., Kuroki R, Inaka K, Taniyama Y, Kidokoro S, Matsushima M, Kikuchi M, Yutani K, Biochemistry. 1992 Sep 8;31(35):8323-8. PMID:1525170
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