Probing the polarity and water environment at the protein-peptide binding interface using tryptophan analogues |
| |
Authors: | Yi-Ting Chen Wei-Chih Chao Hsiou-Ting Kuo Jiun-Yi Shen I-Han Chen Hsiao-Ching Yang Jinn-Shyan Wang Jyh-Feng Lu Richard P. Cheng Pi-Tai Chou |
| |
Affiliation: | 1. Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan;2. Department of Chemistry, Fu-Jen Catholic University, New Taipei City 24205, Taiwan;3. School of Medicine, Fu-Jen Catholic University, New Taipei City 24205, Taiwan |
| |
Abstract: | 7-Azatryptophan and 2,7-diazatryptophan are sensitive to polarity changes and water content, respectively, and should be ideal for studying protein-protein and protein-peptide interactions. In this study, we replaced the tryptophan in peptide Baa (LKWKKLLKLLKKLLKLG-NH2) with 7-azatryptophan or 2,7-diazatryptophan, forming (7-aza)Trp-Baa and (2,7-aza)Trp-Baa, to study the calmodulin (CaM)-peptide interaction. Dramatic differences in the (7-aza)Trp-Baa and (2,7-aza)Trp-Baa fluorescence properties between free peptide in water and calmodulin-bound peptide were observed, showing a less polar and water scant environment at the binding interface of the peptide upon calmodulin binding. The affinity of the peptides for binding CaM followed the trend Baa (210±10 pM)<(7-aza)Trp-Baa (109±5 pM)<(2,7-aza)Trp-Baa (45±2 pM), showing moderate increase in binding affinity upon increasing the number of nitrogen atoms in the Trp analogue. The increased binding affinity may be due to the formation of more hydrogen bonds upon binding CaM for the Trp analogue with more nitrogen atoms. Importantly, the results demonstrate that (7-aza)Trp and (2,7-aza)Trp are excellent probes for exploring the environment at the interface of protein-peptide interactions. |
| |
Keywords: | Calmodulin Calmodulin binding peptide Unnatural tryptophan analogues Water catalyzed excited state proton transfer |
本文献已被 ScienceDirect 等数据库收录! |
|