Entropic Stabilization of a Mutant Human Lysozyme Induced by Calcium Binding

  • Kuroki R
  • Kawakita S
  • Nakamura H
 et al. 
  • 1

    Readers

    Mendeley users who have this article in their library.
  • N/A

    Citations

    Citations of this article.

Abstract

The stabilization mechanism of the mutant human lysozyme with a calcium binding site (D86/92) was investigated by using calorimetric approaches. By differential scanning calorimetry, the enthalpy change (DELTA-H) in the unfolding of holo-D86/92 was found to be 6.8 kcal/mol smaller than that of the wild-type and apo-D86/92 lysozymes at 85-degrees-C. However, the unfolding Gibbs energy change (DELTA-G) of the holo mutant was 3.3 kcal/mol greater than the apo type at 85-degrees-C, indicating a significant decrease of entropy (T-DELTA-S = 10.1 kcal/mol) in the presence of Ca2+. Subsequently, the Ca2+ binding process in the folded state of the mutant was analyzed by using titration isothermal calorimetry. The binding enthalpy change was estimated to be 4.5 kcal/mol, and DELTA-G was -8.1 kcal/mol at 85- degrees- C, which indicates that the binding was caused by a large increase in entropy (T-DELTA-S = 12.6 kcal/mol). From these analyses, the unfolded holo mutant was determined to bind Ca2+ with a binding DELTA-G of - 4.8 kcal/mol (DELTA-H = -2.6 kcal/mol, T-DELTA-S = 2.2 kcal/mol) at 85-degrees-C. Therefore, the major cause of stabilization of holo-D86/92 is the decrease in entropy of the peptide chain due to Ca2+ binding to the unfolded protein

Author-supplied keywords

  • BINDING
  • CALCIUM
  • CHAIN
  • Calorimetry
  • DIFFERENTIAL SCANNING CALORIMETRY
  • ENERGY
  • ENTHALPY CHANGES
  • Enthalpy
  • Entropy
  • LYSOZYME
  • MECHANISM
  • PEPTIDE
  • PROTEIN
  • SCANNING CALORIMETRY
  • SITE
  • STABILITY
  • STABILIZATION
  • STATE
  • Thermodynamics
  • Titration Calorimetry
  • Unfolded State
  • Unfolding
  • apo
  • binding site
  • calcium binding
  • ccod_author92
  • human
  • mutant

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

There are no full text links

Authors

  • R Kuroki

  • S Kawakita

  • H Nakamura

  • K Yutani

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free