The function of tryptophan residues in membrane proteins

作者：Marianne Schiffer, Chen-Hsien Chang, F.J. Stevens · 发表于：Protein Engineering Design and Selection · 年份：1992 · DOI：10.1093/protein/5.3.213 · 被引用次数：348 · 研究领域：Photosynthetic Processes and Mechanisms、Protein Structure and Dynamics、Origins and Evolution of Life

Membrane proteins have a significantly higher Trp content than do soluble proteins. This is especially true for the M and L subunits of the photosynthetic reaction center from purple bacteria. The Trp residues are not uniformly distributed through the membrane but are concentrated at the periplasmic side of the complex. In addition, Trp residues are not randomly aligned. Within the protein subunits, many form hydrogen bonds with carbonyl oxygens of the main chain, thereby stabilizing the protein. On the surface of the molecule, they are correctly positioned to form hydrogen bonds with the lipid head groups while their hydrophobic rings are immersed in the lipid part of the bilayer. These observations suggest that Trp residues are involved in the translocation of protein through the membrane and that following translocation, Trp residues serve as anchors on the periplasmic side of the membrane.