Helix‐helix transition of α‐helical poly(β‐phenethyl L‐aspartae) observed in the lyotropic liquid‐crystalline state

Conformational Analysis of α-Helical Polypeptides in Two Opposite Screw Forms. A Combined Use of 2H NMR and MD Simulation

“…7, 1995 (fl.voc), and qh is the component of quadrupolar interaction tensor along the a-helical axis. The quadrupolar splitting due to the i-th C-D bond of the side chain may be expressed as fl.v;=(3/2)(e2:Q to( 3(cos:0)-1 )s (3) where (e 2 qQ/h)co is the quadrupolar coupling constant of a given C-D bond, e indicates the inclination of the C-D bond relative to the molecular axis, and < ) designates an average taken over all conformations of the side chain. In other words, the quadrupolar splitting data observed ·for the individual CD bonds include information concerning the rotational characteristics of the constituent bonds, thus the conformation of the side chain.…”

“…While the IX-helical PBLG is known only in the right-handed form, PPLA can be either in the right-or left-handed arrangement depending on the solvent or temperature. 3 (Hereafter we distinguish the handedness of the screw sense by prefixing r-or I-to PPLA or PBLG.) The latter behavior is widely known as a character----{HN-TH-co};-cH2coo(cH2M PPLA ---{HN-TH-co};-(CH2hCoocH24>…”

Conformational Transformation of Poly(β-phenetyl-L-aspartate) in Block Copolymer with Polystyrene in 1,1,2,2-Tetrachloroethane

“…Furthermore, side-chain C " H 2 protons also were affected by the temperature elevation, i.e., the increase of signal intensity at 4.25 ppm, indicating the formation of more proliferated side-chain conformations. [9][10][11][12][13] Again the signals were completely reversible on heating and cooling cycles.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] In particular, RH and LH conformations are interesting because their formation can be reversibly controlled by thermal stimulus. [5][6][7][8] The helical-sense inversion has been reported to be caused by difference in the conformational entropy of the side-chain between the two opposite helical structures. [9][10][11][12][13] In addition to the side-chain groups, chain termini of poly(aspartate ester)s should have a significant effect on their conformations, thus, allowing us to control them.…”

“…[5][6][7][8] The helical-sense inversion has been reported to be caused by difference in the conformational entropy of the side-chain between the two opposite helical structures. [9][10][11][12][13] In addition to the side-chain groups, chain termini of poly(aspartate ester)s should have a significant effect on their conformations, thus, allowing us to control them. Although a number of reports addressing the effect has been limited so far, Ushiyama et al have demonstrated that attaching helical poly(-benzyl-L-glutamate) (BG) segment at the chain terminus of poly(-phenethyl-L-aspartate) (PA) by block copolymerization have a significant influence on the helical-sense inversion of the PA segment.…”