PDBsum entry 1c43

Hydrolase

PDB id: 1c43

Contents

Protein chain

130 a.a. *

Metals

_NA

Waters ×179

* Residue conservation analysis

PDB id:

1c43

Name:

Hydrolase

Title:

Mutant human lysozyme with foreign n-terminal residues

Structure:

Protein (human lysozyme). Chain: a. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli. Expression_system_taxid: 562. Other_details: synthetic gene

Resolution:

1.80Å R-factor: 0.164

Authors:

K.Takano,K.Tsuchimori,Y.Yamagata,K.Yutani

Key ref:

K.Takano et al. (1999). Effect of foreign N-terminal residues on the conformational stability of human lysozyme. Eur J Biochem, 266, 675-682. PubMed id: 10561612 DOI: 10.1046/j.1432-1327.1999.00918.x

Date:

03-Aug-99 Release date: 20-Aug-99

Protein chain

P61626  (LYSC_HUMAN) -  Lysozyme C from Homo sapiens

Seq: 148 a.a.

Struc: 130 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.3.2.1.17 - lysozyme.
• Reaction: Hydrolysis of the 1,4-beta-linkages between N-acetyl-D-glucosamine and N-acetylmuramic acid in peptidoglycan heteropolymers of the prokaryotes cell walls.

DOI no: 10.1046/j.1432-1327.1999.00918.x

Eur J Biochem 266:675-682 (1999)

PubMed id: 10561612

Effect of foreign N-terminal residues on the conformational stability of human lysozyme.

K.Takano, K.Tsuchimori, Y.Yamagata, K.Yutani.

ABSTRACT

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.

Selected figure(s)

Figure 2.
Fig. 2. Typical excess heat capacity curves of (a) the wild-type (b) K1A and (c) Met(-1) of human lysozyme at pH 2.72, 2.77 and 2.65, respectively. The increments of excess heat capacity are 10 kJ·mol^-1·K^-1.

Figure 3.
Fig. 3. Stereodrawings of (A) the K1M (B) K1A and (C) Gly(-1) structures in the vicinity of the N-terminal of human lysozyme. Solvent water molecules are drawn as crossed circles. Broken lines represent hydrogen bonds. The structure was generated with the program ORTEP [42].

The above figures are reprinted by permission from the Federation of European Biochemical Societies: Eur J Biochem (1999, 266, 675-682) copyright 1999.

Figures were selected by an automated process.