Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/149967

Download PDF (Published version) (Adobe Acrobat PDF, -1 bytes)

Title

Correlation of electronic structures of three cyclic dipeptides with their photoemission spectra

Author(s)

Arachchilage, Anoja P. Wickrama;  Wang, Feng;  Feyer, Vitaliy;  Plekan, Oksana;  Prince, Kevin C.

Abstract

We have investigated the electronic structure of three cyclic dipeptides: cyclo (Glycyl-Glycyl) (cGG), cyclo(Leucyl-Prolyl) (cLP), and cyclo(Phenylalanyl-Prolyl) (cPP). These compounds are biologically active and cLP and cPP are derived from cGG (also known as diketopiperazine), by the addition of the respective functional groups of the amino acids, namely, phenyl, alkyl or a fused pyrrolidine ring (proline). Experimental valence and core level spectra have been interpreted in the light of theoretical calculations to identify the basic chemical properties associated with the central ring, and with the additional functional groups in cLP and cPP. The theoretically simulated spectra of all three cyclic dipeptides in both valence and core spaces agreed reasonably well with the experimental spectra. The three molecules displayed similarities in their core spectra, suggesting that the diketopiperazine structure plays an important role in determining the inner shell spectrum. The experimental C 1s spectra of cLP and cPP are analogous but differ from cGG due to the side chains attached to the diketopiperazine structure. Single spectral peaks in the N 1s (and O 1s) spectra of the dipeptides indicate that the chemical environment of the nitrogen atoms (and oxygen atoms) are very similar, although they show a small splitting in the simulated spectra of cPL and cPP, due to the reduction of their point group symmetry. Valence band spectra of the three dipeptides in the frontier orbital region of 9-11 eV exhibit similarities; however theoretical analysis shows that significant changes occur due to the involvement of the side chain in the frontier orbitals of cPP, while lesser changes are found for cLP.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Molecular Simulation

Source

Journal of Chemical Physics, Vol. 133, no. 17 (2010), Article no. 174319

Publication year

2010

FOR Code(s)

0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics;  0306 Physical Chemistry (Incl. Structural);  0904 Chemical Engineering

Keyword(s)

Cyclic dipeptides;  Electronic structure;  Photoemission spectra

Publisher

American Institute of Physics

ISSN

0021-9606

Publisher URL

http://dx.doi.org/10.1063/1.3499740

Copyright

Copyright © 2010 American Institute of Physics. Published version of the paper reproduced here with the kind permission of the publisher.

Additional information

This article was selected for inclusion in the Virtual Journal of Biological Pyhsics Research, Vol. 20, no. 10 (Nov 2010). See: http://vjbio.aip.org/dbt/dbt.jsp?KEY=VIRT02&Volume=20&Issue=10

Full text

Peer reviewed