Effect of foreign N-terminal residues on the conformational stability of human lysozyme.Takano, K., Tsuchimori, K., Yamagata, Y., Yutani, K.
(1999) Eur.J.Biochem. 266: 675-682
- PubMed: 10561612
- Primary Citation of Related Structures:  1C43, 1C46
- PubMed Abstract:
- Contribution of Hydrophobic Residues to the Stability of Human Lysozyme: Calorimetric Studies and X-Ray Structural Analysis of the Five Isoleucine to Valine Mutants
Takano, K.,Ogasawaha, K.,Kaneda, H.,Yamagata, Y.,Fujii, S.,Kanaya, E.,Kikuchi, M.,Oobatake, M.,Yutani, K.
(1995) J.Mol.Biol. 254: 62
To minutely understand the effect of foreign N-terminal residues on the conformational stability of human lysozyme, five mutant proteins were constructed: two had Met or Ala in place of the N-terminal Lys residue (K1M and K1A, respectively), and othe ...
To minutely understand the effect of foreign N-terminal residues on the conformational stability of human lysozyme, five mutant proteins were constructed: two had Met or Ala in place of the N-terminal Lys residue (K1M and K1A, respectively), and others had one additional residue, Met, Gly or Pro, to the N-terminal Lys residue (Met(-1), Gly(-1) and Pro(-1), respectively). The thermodynamic parameters for denaturation of these mutant proteins were examined by differential scanning calorimetry and were compared with that of the wild-type protein. Three mutants with the extra residue were significantly destabilized: the changes in unfolding Gibbs energy (DeltaDeltaG) were -9.1 to -12.2 kJ.mol-1. However, the stability of two single substitutions at the N-terminal slightly decreased; the DeltaDeltaG values were only -0.5 to -2.5 kJ.mol-1. The results indicate that human lysozyme is destabilized by an expanded N-terminal residue. The crystal structural analyses of K1M, K1A and Gly(-1) revealed that the introduction of a residue at the N-terminal of human lysozyme caused the destruction of hydrogen bond networks with ordered water molecules, resulting in the destabilization of the protein.
Institute for Protein Research, Osaka University, Yamadaoka, Suita, Osaka, Japan.