Yamagishi Hiroki, Sato Hisako, Kawamura Izuru
Graduate School of Engineering Science, Yokohama National University, Yokohama, Japan.
Graduate School of Science and Engineering, Ehime University, Matsuyama, Japan.
Chirality. 2021 Oct;33(10):652-659. doi: 10.1002/chir.23343. Epub 2021 Jul 27.
Microcrystals of l-Asn-d-Trp-l-Phe-NH (NdWFamide), a tripeptide derived from Aplysia kurodai that exhibits invertebrate cardiac activity, were evaluated by vibrational circular dichroism (VCD). The chirality of the tryptophan residue at the second position in NdWFamide was associated with the conformation and biological characteristics. The VCD spectrum of NdWFamide was a mirror image of its enantiomer; however, it was significantly different from that of its diastereomer, NWFamide, which is its precursor. The obtained VCD signals of NdWFamide were in good agreement with the VCD signals that were calculated based on the optimized aggregates of NdWFamide, which formed a helical-like backbone conformation. The evaluation of the VCD results revealed the conformation of NdWFamide in the crystalline state and succeeded in distinguishing its stereoisomers. Therefore, this study demonstrates VCD as a useful method for the structural analysis of naturally occurring d-amino acid-containing peptides.
对源自黑尾海兔的具有无脊椎动物心脏活性的三肽l-天冬酰胺-d-色氨酸-l-苯丙氨酸-NH₂（NdWFamide）的微晶进行了振动圆二色性（VCD）评估。NdWFamide中第二个位置的色氨酸残基的手性与构象和生物学特性相关。NdWFamide的VCD光谱是其对映体的镜像；然而，它与其非对映体NWFamide（其前体）的VCD光谱有显著差异。获得的NdWFamide的VCD信号与基于形成螺旋状主链构象的NdWFamide优化聚集体计算出的VCD信号高度一致。对VCD结果的评估揭示了NdWFamide在晶体状态下的构象，并成功区分了其立体异构体。因此，本研究证明VCD是一种用于分析天然含d-氨基酸肽结构的有用方法。
