Quantum mechanical study of (Gly-Pro-Pro) repetitive unit in relation to collagen structure

Abstract

PCILO results concerning the conformational possibility of the (Gly-PrePro) repetitive unit are presented. Using appropriate molecules as models, the conformational space of the various backbone dihedral angles was studied with the pyrrolidine rings left free to adopt the most favorable puckering. The results are in good agreement with available crystallographic data on collagenlike structures. These computations indicate that interchain interactions are only an additional stabilizing factor in triple-helix formation.

From Democritus to Schrödinger: a reflection on quantum molecular modeling

“…In X and Y positions the aminoacids proline (Pro) and hydroxyproline occur frequently and the polymer (Gly-Pro-Pro) n presents physicochemical properties similar to collagen. The conformational preferences of this repetitive tripeptide unit, with each pyrrolidine ring free to take the most favorable puckering, was undertaken using PCILO method [37]. It is to be noted that the left-handed helix results from this tripeptide sequence because there is no freedom rotation around the N-Ca bond which is engaged in the pyrrolidine ring (the rotational parameter u is blocked at around the value ?300°).…”

“…Some studies were also conducted (group experimental: AM Tamburro; theoretical: D. Vasilescu group) on Collagenic and Elastinic structures [37][38][39][40][41][42][43][44][45][46][47]. Conformational analysis on different molecular models was undertaken using methods PCILO, AM1, and ab initio.…”

Quantum conformational studies of model molecules in relation to collagenic structures: Effect of nature and location of aliphatic residues in (gly-R2-pro)n and (gly-pro-R3)n sequences

“…Geometries are taken from [ 15,161 and, in the case of prolyl residue, from [ 171. The y endo and y exo proline puckering have been taken into consideration [6]. The peptide units were taken in their trans conformation (o= 180").…”