Circular dichroism spectra and conformational flexibility of small

Circular dichroism spectra and conformational flexibility of
small biomolecules determined within first-principles
methods
Dr.ssa Elena Molteni
Physics Department, Università degli Studi di Milano, Italy
European Theoretical Spectroscopy Facility (ETSF)
Physics Department, Università degli Studi di Cagliari, Italy
Circular dichroism (CD) results from the difference in absorption between right and left circularly
polarized light by chiral molecules. It is a valuable experimental technique for structural
investigation and allows to obtain information related to molecule chirality, such as the absolute
configuration of small molecules, or secondary structure content in proteins, i.e. their local
arrangement into alpha-helices, beta-sheets, etc, which is very often related to the protein
function.
For peptides (short protein fragments) its application is less straightforward, due to the tendency
of these molecules to adopt multiple conformations at equilibrium, and to the fact that, in such
small systems, spectra may also be affected by the chemical composition of the polypeptide
chain, i.e. by single amino acids. Amino acids, besides being chiral, also display a non-negligible
degree of flexilibity, and their CD spectra contain information on this latter feature, too.
We have implemented the calculation of CD spectra in a computational code which can interface
with existing density functional theory (DFT) software packages. After preliminary tests on very
simple molecules, we have applied it to amino acids, focusing on the conformational dependence
of CD spectra, and to a biologically interesting peptide that can adopt different secondary
structures.
MARTEDI 17 FEBBRAIO ORE 15:00 AULA C
SEMINARIO VALIDO PER I DOTTORANDI DELLA SCUOLA DI DOTTORATO IN FISICA
SEMINARIO ORGANIZZATO NELL'AMBITO DELLE MANIFESTAZIONI PER L'ANNO
INTERNAZIONALE SULLA LUCE UNESCO (IYL2015).
Per ulteriori informazioni rivolgersi a: Prof. G. Cappellini , [email protected]