Zanotti G, Beijer B, Wieland T
C.N.R. Institute of Pharmaceutical Chemistry, University La Sapienza, Rome, Italy.
Int J Pept Protein Res. 1987 Sep;30(3):323-9. doi: 10.1111/j.1399-3011.1987.tb03338.x.
The helicity of the tryptathionine moiety of the phallotoxins has been recognized by comparison with cyclic tryptathionine tripeptides. In order to investigate the influence of the configuration of the component amino acids on the conformation of the cyclic peptides, six analogue thioether tripeptides containing L- and D-alanine and L- and D-cysteine, respectively, have been synthesized. The CD spectra of the peptides are very similar to each other, showing mirror images of the CD of phalloidin and, therefore, negative helicity. The spectra of the D-cysteine containing compounds differ from the L-cysteine containing compounds by their weakly positive ellipticity values around 270 nm. The cyclization reaction of Boc-Hpi-D-Ala-D-Cys(STrt)OCH3, along with the cyclic tripeptide, afforded a cyclic hexapeptide by dimerization. The CD spectrum of the dimer is very similar to that of phalloidin, thus pointing to a positive helicity of its two tryptathionine moieties. The dimeric thioether peptide forms a rather strong complex with Cu2+ ions.
通过与环色氨酸三肽比较，已认识到鬼笔毒素中色氨酸部分的螺旋性。为了研究组成氨基酸的构型对环肽构象的影响，分别合成了六种含有L-和D-丙氨酸以及L-和D-半胱氨酸的类似硫醚三肽。这些肽的圆二色光谱彼此非常相似，呈现出鬼笔环肽圆二色光谱的镜像，因此具有负螺旋性。含D-半胱氨酸的化合物的光谱与含L-半胱氨酸的化合物的光谱不同，在270nm左右其椭圆率值呈弱正性。Boc-Hpi-D-Ala-D-Cys(STrt)OCH3的环化反应与环三肽一起，通过二聚作用生成了一种环六肽。二聚体的圆二色光谱与鬼笔环肽的非常相似，因此表明其两个色氨酸部分具有正螺旋性。二聚硫醚肽与Cu2+离子形成相当强的复合物。
