1I20

MUTANT HUMAN LYSOZYME (A92D)

1I20 の概要

• エントリーDOI: 10.2210/pdb1i20/pdb
• 関連するPDBエントリー: 1I1Z 1I22 1LZ1 2LHM 3LHM
• 分子名称: LYSOZYME C (2 entities in total)
• 機能のキーワード: calcium binding site, mutant human lysozyme, hydrolase
• 由来する生物種: Homo sapiens (human)
• 細胞内の位置: Secreted: P61626
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 14764.70

構造登録者

Kuroki, R. (登録日: 2001-02-05, 公開日: 2001-02-28, 最終更新日: 2024-10-30)

主引用文献

Kuroki, R.,Yutani, K.
Structural and thermodynamic responses of mutations at a Ca2+ binding site engineered into human lysozyme.
J.Biol.Chem., 273:34310-34315, 1998

PubMed Abstract: Structural determinants of Ca2+ binding sites within proteins typically comprise several acidic residues in appropriate juxtaposition. Three residues (Ala-83, Gln-86, and Ala-92) in human lysozyme are characteristically mutated to Lys, Asp, and Asp, respectively, in natural Ca2+ binding lysozymes and alpha-lactalbumins. The effects of these mutations on the stability and Ca2+ binding properties of human lysozyme were investigated using calorimetry and were interpreted with crystal structures. The double mutant, in which Glu-86 and Ala-92 were replaced with Asp, clearly showed Ca2+ binding affinity, whereas neither point mutant showed Ca2+ affinity, indicating that both residues are essential. The further mutation of Ala-83 --> Lys did not affect the Ca2+ binding of the double mutant. The point mutations Ala-83 --> Lys and Glu-86 --> Asp did not affect the stability, whereas the mutation Ala-92 --> Asp was about 1.3 kcal/mol less stable. Structural analyses showed that both Asp-86 and Lys-83 were exposed to solvent. Side chains of Asp-86 and Asp-91 were rotated in opposite directions about chi1 angle, as if to reduce the electrostatic repulsion. The charged amino acids at the Ca2+ binding site did not significantly affect stability of the protein, possibly because of the local conformational change of the side chains.

PubMed: 9852096
DOI: 10.1074/jbc.273.51.34310

実験手法

X-RAY DIFFRACTION (1.9 Å)