Original scientific paper

CD and FTIR Spectroscopic Studies of Carbohydrate-modified Opioid Peptides

Elemér Vass ; Department of Organic Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
Miklós Hollósi ; Department of Organic Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
Štefica Horvat ; Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Zagreb, Croatia
Maja Roščić ; Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Zagreb, Croatia

Abstract

The variety of vital functions played by glycoproteins in many physiological and pathological
processes inspired the design of glycopeptides and the study of the effect of glycosylation on
conformation. This work reports comparative circular dichroism (CD) and Fourier transform
infrared (FTIR) spectroscopic studies on linear and cyclic Amadori and imidazolidinone-type
glycopeptides 3–8 in comparison with spectroscopic data of the non-modified flexible parent
peptides, Leu-enkephalin (H-Tyr-Gly-Gly-Phe-Leu-OH, 1) and its amide (H-Tyr-Gly-Gly-Phe-
-Leu-NH2, 2). The CD and FTIR measurements were performed in different solvents in order
to expose the structural and conformational differences caused by a keto-sugar, a rigid 5-membered
imidazolidinone ring and/or cyclization. The combined application of CD and FTIR
spectroscopy allowed to evaluate the relative amount of the extended and folded conformers of
Amadori as well as imidazolidinone compounds and proved to be an effective tool for characterization
of their structural features leading to a deeper understanding of their conformational
behaviour.

Keywords

glycopeptides; Amadori; imidazolidinone; conformational analysis; circular dichroism; IR spectroscopy

Hrčak ID:

31192

URI

https://hrcak.srce.hr/31192

Publication date:

31.12.2008.

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