<sup>13</sup>C nmr study of the helix–coil transition of poly‐N<sup>5</sup>‐(3‐hydroxypropyl)‐<scp>L</scp>‐glutamine

Blasi, R. Di; Verdini, A. S.

doi:10.1002/bip.1974.360130411

Cited by 8 publications

(2 citation statements)

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“…Another peak appears at 57.2 and 176.9 ppm for C and C 0 =O, respectively, at CD 3 OD 60 % where the random coil to helix transition occurs. 34 The intensity of these peaks increases rapidly with increase of CD 3 OD content. It was further observed that the transition region of coil to helix shifts to higher CD 3 OD contents with increase of the temperature.…”

Section: Resultsmentioning

confidence: 94%

13C NMR Relaxation Study of Segmental Motion of Poly(Nε-hydroxyethyl L-glutamine) in Aqueous Solution

Uchino

Hiraoki

Tsutsumi

2004

Polym J

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To study the segmental motion of poly(N "-hydroxyethyl L-glutamine) (PHEG) in aqueous solution, the 13 C spin-lattice relaxation time (T 1) and the nuclear Overhauser enhancement (NOE) were measured at six resonance frequencies (! C =2) ranging from 15 to 150 MHz and at 100 MHz, respectively, at the temperatures from 20 to 90 C. For the backbone C, plots of logðT 1 =! C Þ against logð! C Þ gave the well superposed master curve, showing that the frequency-temperature reduction rule is realized. The shift factor obeyed the Arrhenius type temperature dependence with the activation energy of 29.6 kJ mol À1. Using this activation energy for the temperature dependence of the correlation time, the master curve and NOE were well reproduced by the Dejean-Lauprêtre-Monnerie (DLM) model. One of parameters relating to the segmental motion was 0 = 1 ¼ 5, where 0 and 1 are the correlation times for the isolated single and correlated pair conformational transitions, respectively. Comparison of this parameter with that for other vinyl polymers showed that PHEG having planar peptide groups in the backbone belongs to polymer group with smaller values of 0 = 1. 0 = 1 was discussed in the relation to the distribution width of the correlation time. The spectral density function Jð!Þ has the exponent to the correlation time a as !Jð!Þ $ ð! a Þ 0:61 in the region of ! a < 0:2 which is close to the value of 0.5 from the DLM model.

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Section: Resultsmentioning

confidence: 94%

13C NMR Relaxation Study of Segmental Motion of Poly(Nε-hydroxyethyl L-glutamine) in Aqueous Solution

Uchino

Hiraoki

Tsutsumi

2004

Polym J

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“…Further evidence that polydispersity is the basis for double peaks has been presented by Di Blasi and Verdini. 25 They have shown that lowmolecular-weight poly[N5-(3-hydroxy propy1)~-glutamine] in water/ methanol mixtures exhibits peak doubling in the carbon-13 nmr spectrum. On fractionation, the double-peak character is reduced.…”

Section: Resultsmentioning

confidence: 99%

Origin of multipeak behavior in the NMR spectra of poly(L‐glutamic acid)

Lader

Mandelkern

1979

Biopolymers

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SynopsisThe previous report that poly (L-glutamic acid) exhibits doubled resonances in the helix-coil transition region by either proton or carbon-13 nmr resolves the question of whether or not this behavior is limited to uncharged polypeptides in organic solvents, as had been previously thought. In the present work, we show that the underlying principle causing this anomalous double-peak behavior is due to molecular-weight polydispersity of the sample. The molecular-weight range in which this phenomenon is observed is largely dependent on the values of u, the nucleation or cooperativity factor. The principles developed are shown to encompass all classes of polypeptides in a very natural way and to explain the key experimental data in the literature.

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Conformational behavior of poly‐N⁵‐(3‐hydroxypropyl)‐L‐glutamine in water–methanol mixtures studied by ¹³C nmr and CD spectroscopy

Blasi¹,

Verdini²

1974

Biopolymers

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SynopsisThe helix-coil transition of poly-N~-(3-hydroxypropyl>~-glutamine (PHPLG) has been studied in methanol-water by CD and cmr spectroscopy. For polydisperse PHPLG, two separate peaks arising from residues in helical and random-coil conformations are observed during the transition for both main-chain carbons. These results are discussed and compared to those observed in the case of a polymer sample obtained by racemization of PHPLG in 0.1 M NaOH and of PHPLG samples of controlled molecular weight and dispersity. The dominant influence of the molecular-weight heterogeneity on the double-peak phenomenon has been verified. The linewidths and chemical shift of the 13C resonances are discussed in terms of side-chain-main-chain interactions and side-chain solvation.

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¹³C nmr study of the helix–coil transition of poly‐N⁵‐(3‐hydroxypropyl)‐L‐glutamine

Cited by 8 publications

References 10 publications

13C NMR Relaxation Study of Segmental Motion of Poly(Nε-hydroxyethyl L-glutamine) in Aqueous Solution

13C NMR Relaxation Study of Segmental Motion of Poly(Nε-hydroxyethyl L-glutamine) in Aqueous Solution

Origin of multipeak behavior in the NMR spectra of poly(L‐glutamic acid)

Conformational behavior of poly‐N⁵‐(3‐hydroxypropyl)‐L‐glutamine in water–methanol mixtures studied by ¹³C nmr and CD spectroscopy

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13C nmr study of the helix–coil transition of poly‐N5‐(3‐hydroxypropyl)‐L‐glutamine

Cited by 8 publications

References 10 publications

13C NMR Relaxation Study of Segmental Motion of Poly(Nε-hydroxyethyl L-glutamine) in Aqueous Solution

13C NMR Relaxation Study of Segmental Motion of Poly(Nε-hydroxyethyl L-glutamine) in Aqueous Solution

Origin of multipeak behavior in the NMR spectra of poly(L‐glutamic acid)

Conformational behavior of poly‐N5‐(3‐hydroxypropyl)‐L‐glutamine in water–methanol mixtures studied by 13C nmr and CD spectroscopy

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¹³C nmr study of the helix–coil transition of poly‐N⁵‐(3‐hydroxypropyl)‐L‐glutamine

Conformational behavior of poly‐N⁵‐(3‐hydroxypropyl)‐L‐glutamine in water–methanol mixtures studied by ¹³C nmr and CD spectroscopy