Uozumi Ryuichi, Takahashi Tsuyoshi, Yamazaki Toshimasa, Granholm Viktor, Mihara Hisakazu
Department of Bioengineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, B40 4259 Nagatsuta, Yokohama 226-8501, Japan.
Biopolymers. 2010;94(6):830-42. doi: 10.1002/bip.21464.
To examine stabilizing effects of the base pair interaction on a protein scaffold, various peptides with L-α-amino acids bearing a nucleobase in the side chain (nucleobase amino acids; NBAs) were designed based on a G-peptide β-hairpin structure, and their conformational properties were investigated by circular dichroism and NMR spectroscopy. Thermodynamic analyses based on the chemical shifts showed that adenine-thymine pairing in a diagonal fashion at positions 4 and 15 (2AT) enhanced thermal stability of the peptide conformation by more than 30 K as compared with the wild-type G-peptide. In NOESY spectrum, not only numerous nonadjacent crosspeaks but also long-range crosspeaks between the nucleobases were observed in some peptides with the base pairing. NMR structure calculations of the 2AT peptide confirmed that cross-strand pairing of the nucleobases occurs on the well-defined β-hairpin structure as designed. Taken together, the base pairing in an appropriate position and orientation facilitates folding and stabilization of a native-like β-hairpin structure.
为了研究碱基对相互作用对蛋白质支架的稳定作用，基于G肽β-发夹结构设计了各种在侧链带有核碱基的L-α-氨基酸肽（核碱基氨基酸；NBA），并通过圆二色光谱和核磁共振光谱研究了它们的构象性质。基于化学位移的热力学分析表明，与野生型G肽相比，在第4和15位以对角方式形成的腺嘌呤-胸腺嘧啶配对（2AT）使肽构象的热稳定性提高了30 K以上。在NOESY谱中，在一些具有碱基配对的肽中不仅观察到许多非相邻交叉峰，还观察到核碱基之间的长程交叉峰。2AT肽的核磁共振结构计算证实，核碱基的跨链配对发生在设计的明确β-发夹结构上。综上所述，在适当的位置和取向下的碱基配对有助于类天然β-发夹结构的折叠和稳定。
