title: Screw-sense inversion characteristic of alpha-helical poly(beta-p-chlorobenzyl L-aspartate) and comparison with other related polyaspartates.
abstract: This is one of a series of studies on the reversal of the helix sense of polyaspartates originated from the pioneering work of Goodman and his associates in 1960s. Poly(beta-p-chlorobenzyl L-aspartate) (PClBLA) is one of the well-studied polyaspartate derivatives in both solution and the solid state. The chemical structure of PClBLA differs from those of poly(beta-benzyl L-aspartate) (PBLA) and poly(beta-phenethyl L-aspartate) (PPLA) only at the terminal of the relatively long side chain. PBLA takes a left-handed form (L) in conventional helicoidal solvents and does not exhibit any screw-sense inversion. In contrast to PBLA, both PClBLA and PPLA form a right-handed helix (R) in chlorinated alkane solvents and exhibits a reversal of alpha-helix sense at higher temperatures. Yet the transition behaviors in the presence of denaturant acid are quite different between these two polymers. While PPLA exhibits transitions such as R --> L --> coil by lowering temperature, PClBLA directly goes into the coil state without showing the reentrant L form. The cause of these phenomenological differences among these polymers has been investigated by constructing the phase diagram.
authors.affiliation: Department of Applied Chemistry, Tokyo Polytechnic University, 1583 Iiyama, Atsugi 243-0297, Japan. aabe@chem.t-kougei.ac.jp
authors.forename: Akihiro
authors.initials: A
authors.lastname: Abe
authors.forename: Kentaro
authors.initials: K
authors.lastname: Hiraga
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Imada
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Hiejima
authors.forename: Hidemine
authors.initials: H
authors.lastname: Furuya
mesh_terms: D001593:Benzyl Compounds / Q000737:chemistry; D002942:Circular Dichroism; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry*; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D012997:Solvents
chemical_list: D001593:Benzyl Compounds; D010455:Peptides; D012997:Solvents; C017645:polyaspartate