246L

THE RESPONSE OF T4 LYSOZYME TO LARGE-TO-SMALL SUBSTITUTIONS WITHIN THE CORE AND ITS RELATION TO THE HYDROPHOBIC EFFECT

246L の概要

• エントリーDOI: 10.2210/pdb246l/pdb
• 関連するPDBエントリー: 2LZM 3LZM
• 分子名称: T4 LYSOZYME, CHLORIDE ION, 2-HYDROXYETHYL DISULFIDE, ... (4 entities in total)
• 機能のキーワード: hydrolase, o-glycosyl, glycosidase, bacteriolytic enzyme
• 由来する生物種: Enterobacteria phage T4
• 細胞内の位置: Host cytoplasm : P00720
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 18777.42

構造登録者

Xu, J.,Baase, W.A.,Baldwin, E.,Matthews, B.W. (登録日: 1997-10-22, 公開日: 1998-03-18, 最終更新日: 2024-02-14)

主引用文献

Xu, J.,Baase, W.A.,Baldwin, E.,Matthews, B.W.
The response of T4 lysozyme to large-to-small substitutions within the core and its relation to the hydrophobic effect.
Protein Sci., 7:158-177, 1998

PubMed Abstract: To further examine the structural and thermodynamic basis of hydrophobic stabilization in proteins, all of the bulky non-polar residues that are buried or largely buried within the core of T4 lysozyme were substituted with alanine. In 25 cases, including eight reported previously, it was possible to determine the crystal structures of the variants. The structures of four variants with double substitutions were also determined. In the majority of cases the "large-to-small" substitutions lead to internal cavities. In other cases declivities or channels open to the surface were formed. In some cases the structural changes were minimal (mainchain shifts < or = 0.3 A); in other cases mainchain atoms moved up to 2 A. In the case of Ile 29 --> Ala the structure collapsed to such a degree that the volume of the putative cavity was zero. Crystallographic analysis suggests that the occupancy of the engineered cavities by solvent is usually low. The mutants Val 149 --> Ala (V149A) and Met 6 --> Ala (M6A), however, are exceptions and have, respectively, one and two well-ordered water molecules within the cavity. The Val 149 --> Ala substitution allows the solvent molecule to hydrogen bond to polar atoms that are occluded in the wild-type molecule. Similarly, the replacement of Met 6 with alanine allows the two solvent molecules to hydrogen bond to each other and to polar atoms on the protein. Except for Val 149 --> Ala the loss of stability of all the cavity mutants can be rationalized as a combination of two terms. The first is a constant for a given class of substitution (e.g., -2.1 kcal/mol for all Leu --> Ala substitutions) and can be considered as the difference between the free energy of transfer of leucine and alanine from solvent to the core of the protein. The second term can be considered as the energy cost of forming the cavity and is consistent with a numerical value of 22 cal mol(-1) A(-3). Physically, this term is due to the loss of van der Waal's interactions between the bulky sidechain that is removed and the atoms that form the wall of the cavity. The overall results are consistent with the prior rationalization of Leu --> Ala mutants in T4 lysozyme by Eriksson et al. (Eriksson et al., 1992, Science 255:178-183).

PubMed: 9514271

実験手法

X-RAY DIFFRACTION (1.8 Å)