Nmr study of poly(aspartic acid). I. α‐ and β‐Peptide bonds in poly(aspartic acid) prepared by thermal polycondensation

Pivcová, H.; Saudek, Vladimı́r; Drobník, J.; Vlasak, Jirina

doi:10.1002/bip.1981.360200804

Cited by 41 publications

(22 citation statements)

References 30 publications

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“…The poly(Asp) samples prepared by thermal polycondensation of aspartic acid in solid state contain both R-and -peptide bonds in the main chain. 8 These polymers resemble real proteins in certain aspects and are expected to have a wide application in various cosmetic and sanitary products. Poly(Asp) are especially suited for the present purpose, since they have a relatively narrow molecular weight distribution (M w /M n ) 1.1) in addition to a low degree of polymerization (29 and 12); it is so low that it might well be called oligo(aspartate).…”

Section: Introductionmentioning

confidence: 99%

Effect of Polymer Size on the Polyelectrolyte−Surfactant Interaction

Jun¹,

Takisawa²,

Shirahama³

et al. 1997

J. Phys. Chem. B

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The interaction between alkylpyridinium (C 12 and C 14 ) chloride and sodium poly(aspartate) with different molecular weights is investigated in the presence of 10 mM NaCl by means of a potentiometric titration method using a surfactant-selective electrode at 25°C. The effect of polymer size on the binding process is especially focused on: the critical aggregation concentration increases and the apparent cooperativity of binding decreases with the decreasing of polyelectrolyte molecular weight. Binding isotherms are analyzed by direct calculation of a matrix expressing the partition function and compared with the behavior in other polyelectrolyte-surfactant systems. It is found that the binding constant prominently depends on the polymer chain length when the number of binding sites is less than ca. 35. Such an end effect may be associated with the less effective superimposition of electrostatic potentials around the polymer chain in small-sized polymers. Model calculation is carried out by both the matrix method and the Satake-Yang equation, while the matrix one fits the experimental data better for the short-chain polyelectrolyte.

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Section: Introductionmentioning

confidence: 99%

Effect of Polymer Size on the Polyelectrolyte−Surfactant Interaction

Jun¹,

Takisawa²,

Shirahama³

et al. 1997

J. Phys. Chem. B

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“…For instance, the titration curve of poly(a-Glu) obtained in the presence of 2M NaCl or 0.01M MgC12 and plotted according to Eq. (1) is almost a straight line, parallel with the x-axis, for 0.1 < a < 0.8. 16 The experimental data may be evaluated according to Eq.…”

Section: Discussionmentioning

confidence: 98%

Use of potentiometric titration for determination of α‐ and ω‐peptide bonds in poly(aspartic acid) and poly(glutamic acid)

Saudek

1981

Biopolymers

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SynopsisPolypeptides of dicarboxylic amino acids having the monomer units linked in a-and o-peptide bonds contain two kinds of carboxyls of different acidity. How well potentiometric titration can distinguish these two carboxyls and so characterize the nature of the peptide bonds is evaluated critically. An analysis of the equation describing the dependence of pH on the degree of neutralization based on neglecting the polymer effect and a discussion of the dissociation behavior of polyanions show that the method of evaluating experimental data found in the literature is incorrect. Nevertheless, if a conformational transition does not interfere, some useful and reliable information may be gained by this method; namely, an indication of the presence of two different peptide bonds, their mole ratio, and an approximate pK value for the carboxyl of the amino acid linked in the w-peptide bond. The presence of two types of carboxyls complicates the evaluation of the titration curves in the conformation studies.

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“…Earlier structural analyses demonstrated that β-Asp units account for 70 % of the total composition of tPAA, indicating that tPAA is composed of a high proportion of β-peptides. The analyses also showed that tPAA contains equivalent moles of D-and L-Asp units, with branching and cross-linking as unnatural structures, in addition to β-Asp units [45][46][47][48][49]. As unnatural structures in polymer materials generally affect the biodegradability of the material, tPAA biodegradability should be carefully considered in its applications.…”

Section: Paamentioning

confidence: 98%