The Effects of Biological Environments on the Electron-Relay Functionality of Tryptophan Residues in Proteins

• Published in: Chemphyschem Vol. 13; no. 1; pp. 183 - 192
• Main Authors: Chen, Xiaohua, Dai, Hongjing, Li, Jilai, Huang, Xuri, Wei, Zidong
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 16.01.2012; WILEY‐VCH Verlag; Wiley
• Subjects: amino acids; Biological and medical sciences; density functional calculations; electron transfer; Electron Transport; Electrons; Fundamental and applied biological sciences. Psychology; Interactions. Associations; Intermolecular phenomena; Lewis Acids - chemistry; Metals - chemistry; Molecular biophysics; noncovalent interactions; proteins; Proteins - chemistry; Quantum Theory; Tryptophan - chemistry; α-Aminoacid; density functional calculations; Aminoacid; Biochemical compound; proteins; amino acids; Electron transfer; Tryptophan; Indole derivatives; noncovalent interactions; Protein
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201100713

Clarifying the contribution of tryptophan (Trp) to electron‐transfer (ET) processes in different protein surroundings can help to understand the effective pathway of ET in proteins. Interactions between Trp residues and protein microsurroundings involve intermolecular H‐bonds, cation and π‐electron clouds of aromatic rings, the secondary structure and π orbital of aromatic rings, and so on. Detailed analyses reveal that the microsurroundings play an important role in modulating the electron‐relay function of Trp in proteins. Generally, microsurroundings with strong Lewis acidity inhibit electron hole transport through Trp residues. Systems with weak Lewis acidity finely tune the electron‐relay ability of Trp in proteins, while those with strong Lewis basicity strongly enhance the electron‐relay ability of Trp residues. The role of tryptophan: Protein microsurroundings with a strong Lewis acidity inhibit electron‐hole transport through the indole side chains of tryptophan (Trp) residues in proteins, while systems with a strong Lewis basicity strongly enhance the electron‐relay ability of Trp residues, so that ET can be switched off and on, respectively (see picture).