Conformational Studies of Random DL Copolypeptides in Solution Using High-Resolution Nuclear Magnetic Resonance

Paolillo, Livio; Pa, Temussi; Trivellone, E.; Bradbury, E. Morton; Crane‐Robinson, Colyn

doi:10.1021/ma60036a010

Cited by 6 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…22,23 The R-CH spectrum (δ ∼ 3.9À4.4 ppm) of 1À3 (Figure 2A) is most sensitive to the secondary structure of the peptide block. Based on the peak assignments reported in literature for poly(γ-benzyl glutamate)s in DMF solution, 22 the ZLys segment of 1 should have a predominant random coil structure (absorption centered at about 4.3 ppm) and that of 3 a helical structure (4.0 ppm), as expected. The R-CH spectrum of sample 2 is distinctively different from the other spectra, Macromolecules NOTE exhibiting a very broad multiple signal at 4.0À4.4 ppm, which could not be assigned yet.…”

Section: ' Results and Discussionmentioning

confidence: 99%

“…The true secondary structure of samples 1 – 3 was characterized by means of 1 H NMR (DMF- d 7 , rt) and FT-IR spectroscopy (solid state, rt). , The α-CH spectrum (δ ∼ 3.9–4.4 ppm) of 1 – 3 (Figure A) is most sensitive to the secondary structure of the peptide block. Based on the peak assignments reported in literature for poly(γ-benzyl glutamate)s in DMF solution, the ZLys segment of 1 should have a predominant random coil structure (absorption centered at about 4.3 ppm) and that of 3 a helical structure (4.0 ppm), as expected. The α-CH spectrum of sample 2 is distinctively different from the other spectra, exhibiting a very broad multiple signal at 4.0–4.4 ppm, which could not be assigned yet.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Polypeptide-Based Organogelators: Effects of Secondary Structure

et al. 2011

View full text Add to dashboard Cite

Section: ' Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Polypeptide-Based Organogelators: Effects of Secondary Structure

et al. 2011

View full text Add to dashboard Cite

“…In vitro, however, methods of synthesis of peptides offer no impediment to the placement of mirror-image-related amino acids. Work in this area has discovered the helical changes, following from enantiomerically mixed monomer units, on the conformational properties of peptides derived from α-helical-forming amino acids 9 , 10 . Biologically interesting polymers other than peptides from natural amino acids have been synthesized from mixed enantiomers 11 - 13 …”

Section: Helix Control In Biological Systems (Nucleic Acids and Protementioning

confidence: 99%

Helix control in polymers

Totsingan

Jain

Green

2012

Artificial DNA: PNA & XNA

View full text Add to dashboard Cite

The helix is a critical conformation exhibited by biological macromolecules and plays a key role in fundamental biological processes. Biological helical polymers exist in a single helical sense arising from the chiral effect of their primary units—for example, DNA and proteins adopt predominantly a right-handed helix conformation in response to the asymmetric conformational propensity of D-sugars and L-amino acids, respectively. In using these homochiral systems, nature blocks our observations of some fascinating aspects of the cooperativity in helical systems, although when useful for a specific purpose, “wrong” enantiomers may be incorporated in specific places. In synthetic helical systems, on the contrary, incorporation of non-racemic chirality is an additional burden, and the findings discussed in this review show that this burden may be considerably alleviated by taking advantage of the amplification of chirality, in which small chiral influences lead to large consequences. Peptide nucleic acid (PNA), which is a non-chiral synthetic DNA mimic, shows a cooperative response to a small chiral effect induced by a chiral amino acid, which is limited, however, due to the highly flexible nature of this oligomeric chimera. The lack of internal stereochemical bias is an important factor which makes PNA an ideal system to understand some cooperative features that are not directly accessible from DNA.

show abstract

Experimental study of the conformation of two stereoregular polymethionines: Poly(D‐methionyl‐L‐methionine) and poly(L‐methionyl‐D‐methionyl‐L‐methionine)

1975

View full text Add to dashboard Cite

SynopsisInfrared spectroscopy, X-ray diffraction, and nuclear magnetic resonance spectroscopy have been used in investigating the conformation of two stereoregular polymethionines, poly(D-methionyl-L-methionine) and poly(L-methionyl-D-methionyl-L-methionine). When dissolved in a helicogenic solvent, such as chloroform and hexafluoroisopropanol, the polytripeptide is in an a-helical conformation. A helix-to-coil transition can then be induced by addition of trifluoroacetic acid.On the other hand, it appears that the most stable conformation of poly (D-Met-L-Met) is a fl antiparallel folded structure in which the linear polypeptide segments are near to the planar extension. This structure has been evidenced through X-ray examination of oriented films, casted from solutions in chloroform. It has also been identified in solution in the same solvent, by use of infrared spectroscopy and by measuring the 6~a chemical shift which characterizes the H" proton in the peptide units. This 6~a value is found equal to 5.4 ppm and differs significantly from those which are usually attributed to the a-helical conformation ( 6~a = 4.2 ppm) and to the random coil ( 6~a = 4.6 ppm). The p folded conformation of the poly(D-Met-L-Met) appears to be comparatively less stable than the a-helical one for the poly(L-Met) macromolecular stereoisomer since hexafluoroisopropanol is a helicogenic solvent for this last solute and a destabilizing one for the poly(D-Met-L-Met) /3 folded conformer. X-ray examinations carried out with stretched films, casted from a solution of poly(D-Met-L-Met) in chloroform, result in several data concerning the cross /3 structure of this stereoregular polypeptide in the solid state. 1447 cc) 1975 by John Wiley & Sons, Inc.

show abstract

Conformational Studies of Random DL Copolypeptides in Solution Using High-Resolution Nuclear Magnetic Resonance

Cited by 6 publications

References 0 publications

Polypeptide-Based Organogelators: Effects of Secondary Structure

Polypeptide-Based Organogelators: Effects of Secondary Structure

Helix control in polymers

Experimental study of the conformation of two stereoregular polymethionines: Poly(D‐methionyl‐L‐methionine) and poly(L‐methionyl‐D‐methionyl‐L‐methionine)

Contact Info

Product

Resources

About