80957-35-3Relevant academic research and scientific papers
Conformational Studies of Bis(cyclic tetrapeptide), S,S'-Bis. A Proposed Castanet-type Structure in a Dimethyl Sulfoxide Solution
Shimizu, Toshimi,Tanaka, Yoshio,Tsuda, Keishiro
, p. 3808 - 3816 (2007/10/02)
A bis(cyclic tetrapeptide), S,S'-bis (BCGCSP), was prepared by coupling two homodetic cyclotetrapeptide.The conformations of BCGCSP in solutions were investigated by means of NMR, Raman, and CD spectroscopy.The 1H-NMR data in dimethyl-d6 sulfoxide (Me2SO-d6) demonstrated that the two cyclic skeletons of BCGCSP take the same conformations as that of an authentic cyclic tetrapeptide, cyclo (CGCSP).The 1H-NMR spectrum of CGCSP contains three sets of resonances, corresponding to three different molecular conformations.From the Raman lines of BCGCSP at 529 cm-1 and 683 cm-1 in Me2SO-d6, it is deduced that the two HCα-CβS dihedral angles are 180 deg (trans), while one of the SS-CβCα dihedral angles is 20-30 deg and the other is either near 90 deg or near 180 deg.In addition, the values of two Raman lines predict that the CβS-SCβ dihedral angle is in the range of near 90 deg.Such a conformation around the CβS-SCβ bond is also reasonable in the light of the presence of a CD transition (CS-SC) at λ>250 nm in water.By combining the above data, the CPK molecular model of BCGCSP was constructed.An inspection of the model reveals that this bis(cyclic tetrapeptide) is likely to adopt a "castanet-type" structure in Me2SO-d6.At the same time the individual cyclic skeleton is considered to take three different ring conformations in equilibrium.
