LAUSR

Polyglutamine peptides with an abnormal repeat length are the causative agent of at least nine genetic diseases, known as polyglutamine diseases, which include Huntigton’s disease (HD) and some ataxias, in between the others. In the case of HD the disease appears when the polyQ segment has approximately 36 glutamines (Q). It is known that conformational changes occur and that polyQ aggregation is modulated by the number of Q present in the chain. In the present study, the conformations of monomeric polyQ chains of different lengths (from 7 Q to 45 Q) are systematically investigated by performing all-atom molecular dynamics simulations in explicit water at 310 K. All simulations are performed without any structure constraints. For each system trajectories of 300 ns are generated. Analysis of structures, radius of gyration, root-mean-squared deviation, hydrogen bond analysis, clustering, dihedral angles and analysis of the secondary structures of all studied polyQ repeats are presented. This study provides information about the conformational changes of the considered monomeric peptides with increasing the number of Q. The obtained results are compared with available data. This work confirms that a structural change from the polyQ segment containing 24 Q to the one containing 37 residues occurs.