Serine capped dipeptide N-acetyl-L-serinamide (Ac-Ser-NH 2 ) has been investigated using Fourier transform microwave spectroscopic techniques combined with laser ablation sources. Spectral signatures originating from one dominant species have been detected in the supersonic expansion. Rotational and nuclear quadrupole coupling constants of the two 14 N nuclei have been used in the characterization of a C eq 7 /g-turn structure, which is stabilized by a COÁ Á ÁHN intramolecular hydrogen bond closing a seven-membered ring. Two extra hydrogen bonds involving the polar side chain (-CH 2 OH) further stabilize the structure.The non-observation of C 5 species, attributed to the presence of the polar side chain, is in contrast with the previous gas phase observation of the related dipeptides containing glycine or alanine residues.The A-E splitting pattern arising from the internal rotation of the methyl group has been analyzed and the internal rotation barrier has been determined.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.