A computational study of Trishomocubane amino acid dipeptide

Abstract

4-amino-(D3)-trishomocubane-4-carboxylic acid (tris-amino acid) is a constrained a-amino acid residue that exhibits peculiar conformational characteristics. The aim of the present study is to provide a deeper understanding of these features, which can be used as a guide when chOOSing@shomocubane as suitable building blocks for peptide design. The Ca carbon of@ishomocubane forms part of the cyclic structure, and consequently a peptidic environment was simulated with an acetyl group on its N-terminus and a methyl amide group on its C-terminus. This study involved a complete exploration of the conformational profile of (Yishomocubane using computational techniques.The parm94 parametization of the AMBER oio forc@eld was used to explore the conformational space of the peptide,Q)\xEFshomocubane. The Ramachandran maps computed at the molecular mechanics level' with the parm94 forc@\xEFeld parameters compared reasonably with the corresponding maps computed at the Hartree Fock (HF) level, using the 6-31G* basis set. The results of this study revealed that the conformational profile of the @ishomocubane peptide can be characterized by four low energy regions, viz., C7ax, C7eq, 310 and al helical structures.