Chain conformation of copoly(γ‐methyl D , L ‐glutamate)

et al. 1983

A-B-A tri-block copolymers consisting of DL-isomers of poly(y-methyl glutamate) as the A component and polybutadiene as the B component were prepared. The synthesis was carried out by polymerizing an equimolar mixture of y-methyl D-glutamate and y-methyl Lglutamate NCA with the amine groups capped at both ends of the polybutadiene block or the initiator. By infrared spectroscopy, it was found that the copolypeptide chain block exists not only in an ()(-helical conformation but also in a random coli conformation. On the basis of contact angle measurements, replication electron micrographs, and attenuated total reflection-infrared spectra, it was concluded that the surface of the present block copoly.mer membranes has a microheterophase structure consisting of the copolypeptide and hydrophobic domains, and also has a grainy surface structure with a grain size of 300-500 A. Furthermore, the adsorption of plasma proteins onto these block copolymer membranes was investigated.

mentioning

confidence: 99%

Structure and Properties of Membrane Surfaces of A-B-A Tri-Block Copolymers Consisting of Poly(γ-methyl D,L-glutamate) as the A Component and Polybutadiene as the B Component

Kugo

Murashima

et al. 1983

“…29 We adopted b 0 , h = -600 for PMLG in m-cresol and -615 for PBLG in DMF, respectively, and b0, c = 0 for both cases. 30 Masuda et a/., 24 have pointed out that the IR method is useful for estimating the helix content of solid polypeptide samples, and proposed that the IR peak intensity of the amide Polymer J., Vol. 16, No.…”

Section: Chain Conformation Ofdl-copolypeptidesmentioning

confidence: 99%

Synthesis and Structural Study of the A–B–A Tri-Block Copolymer Consisting of Poly(γ-benzyl D,L-glutamate) or Poly(γ-methyl D,L-glutamate) as the A Component and Polybutadiene as the B Component

Chen

Nakajima

1984

ABSTRACT:A series of A-B-A tri-block copolymers consisting of the D,L-isomers of poly(ybenzyl glutamate) and poly(y-methyl glutamate) as the A component, and polybutadiene as the B component were synthesized. The helical content of the D,L-copolymers in a helicogenic solvent and in a solid state was estimated on the basis of optical rotatory dispersion and infrared spectra. The content of the right-handed ex-helix, the left-handed ex-helix, and random coil conformations of the polypeptide chains was estimated. From wide-angle X-ray diffraction measurements, it was shown that the hexagonal crystalline phase almost disappeared for D,L-copolymer membranes, indicating a breakdown of the ex-helical conformation in the main chains. The microheterophase structure of these block copolymer membranes was studied with an electron microscope and the D,L-block copolymers membranes were found to take on spherical structures even when the volume fractions of the B portion were rather high.

“…In Figure 2, the amide V band of the a-helix was observed at 615 cm-1 for PMLG and PMDG, while thatfor PMDLG was at 620-630cm-1 • Masuda, et al, 4 proposed to estimate the helix content from the peak intensity of the amide V band relative to that at 2950 cm -i, and calculated the helix content of PMDLG from their experimental data.…”

Section: Infrared Absorption Measurementsmentioning

confidence: 99%

“…According to Wada 2 , helices characterized by a unique helical sence are maintained even for o, L-copolymer containing up to about 25-% minor component. This means that minor n-residues(L-residues) may be incorporated in right-handed(left-handed) helix mainly composed of major L-residue(n-residues).More recently, Masuda, et al,4 published results on o, L-copoly(r-methyl glutamate) (PMDLG), polymerized with sodium methoxide as the initiator and dioxane as the solvent, and pointed out that the formation of the left-handed helix is appreciable even at low n-residue content.In the present study, PMDLG covering the whole range of o, L compositions was synthesized 10 …”

mentioning

confidence: 99%

See 1 more Smart Citation

Conformation Studies of Copolypeptides Composed of γ-Methyl-D-glutamate and γ-Methyl-L-glutamate

Nakajima

Itoh

et al. 1973

ABSTRACT:Copolypeptides composed of r-methyl-n-glutamate and r-methyl-L-glutamate covering the whole range of copolymer compositions were synthesized by the NCA method using triethylamine(TEA) as the initiator. The X-ray diffraction measurements for these D, L-copoly(r-methyl glutamate)s in solid state indicated that these copolypeptide molecucles can exist in a conformation very similar to that of the a-helix of PMLG or PMDG. Infrared absorption spectra of solid films were also measured. The sum of right-and left-handed helix contents was determined from intensities of amide V bands. Optical rotatory dispersions of these copolymers in helicogenic solvents were used to ascertain their helical character. The parameter ho of Moffitt-Yangs equation for D, L-copoly(r-methyl glutamate) in helicogenic solvent could give the difference between right-and left-handed helix content. Thus the right-handed helix, left-handed helix, and random coil contents were estimated separately. In order to test the relative stability of helices of these copolypeptides, the optical rotatory dispersions were examined in DCA-DCE mixtures as functions of solvent composition.KEY WORDS Polypeptide / Copolymer of r-Methyl-n-glutamate and r-Methyl-L-glutamate [n,L-copoly(r-methyl glatamate)] / Chain Conformation / X-ray Diffraction / IR / Viscosity / Optical Rotatory dispersion / Helix Stability / The conformation of synthetic homopolypeptides has been investigated in many respects. However, with respect to copolypeptides composed of n-and L-enantiomorphic amino acids a number of problems still remain to be solved. Primarily, the conformation should be discussed in connection with the chain configuration governed by the polymerization mechanism. In this sense, conditions of polymerization, such as the kind of initiator and solvent, and the polymerization field, may be of major importance for chain configuration represented, for example, by the distribution of optical isomers along the chain. Lundberg and Doty1, performed for the first time, a conformation study on o, L-copoly-(r-benzy glutamate) (PBDLG) polymerized from n-and L-N-carboxy anhydrides by using nhexylamine as the initiator and dioxane as the solvent. It was concluded that the chain configuration of PBDLG thus prepared is rather stereo block, i.e., the sequential probability that a n-residue (or L-residue) is succeeded by the same kind of residue is considerably larger than 0.5. Wada 2 , and Tsuboi, et al.3, introduced optical rotatory dispersion and infrared spectra measurements to determine the helix and coil contents, and estimated these contents for PBDLG. According to Wada 2 , helices characterized by a unique helical sence are maintained even for o, L-copolymer containing up to about 25-% minor component. This means that minor n-residues(L-residues) may be incorporated in right-handed(left-handed) helix mainly composed of major L-residue(n-residues).More recently, Masuda, et al.,4 published results on o, L-copoly(r-methyl glutamate) (PMDLG), polymerized with sodium methoxide ...