Physicochemical investigation of <i>k</i>‐carrageenan in the random state

Vreeman, H. J.; Snoeren, T. H. M.; Payens, T.A.J.

doi:10.1002/bip.1980.360190711

Cited by 102 publications

(57 citation statements)

References 34 publications

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“…[4] The polymers appear to be flexible and randomly distributed when immobilized on AP-mica (Figure 1 a,e and Figure S2), different from KClmodified mica, where carrageenans were reported to follow the substrate s crystallographic axes in the cleavage plane. [12] Owing to their polyelectrolytic nature, the intrinsically flexible chains bear, as expected from the Mark-Houwink exponent reported to be just below unity at low ionic strength, [7] a rather extended conformation. In conditions of 100 mm NaCl, the conformation of lambda-carrageenans is preserved, though a little less extended ( Figure 1 f and Figure S2), possibly due to screened repulsive interactions among the sulfate groups.…”

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confidence: 89%

“…The conformational change from disordered carrageenans in the random coil state [7] to ordered, helical chains, is expected to modulate the rigidity of individual polyelectrolyte chains [8] which will be assessed by applying polymer physics concepts to the AFM polymer traces. Commercial iota-and lambdacarrageenan (Figure 1 a,e) were transformed into the Na-form (Table S1) by combining dialysis and ion-exchange.…”

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confidence: 99%

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Unravelling Secondary Structure Changes on Individual Anionic Polysaccharide Chains by Atomic Force Microscopy

2014

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The structural conformations of the anionic carrageenan polysaccharides in the presence of monovalent salt close to physiological conditions are studied by atomic force microscopy. Iota-carrageenan undergoes a coil-helix transition at high ionic strength, whereas lambda-carrageenan remains in the coiled state. Polymer statistical analysis reveals an increase in persistence length from 22.6 AE 0.2 nm in the random coil, to 26.4 AE 0.2 nm in the ordered helical conformation, indicating an increased rigidity of the helical iota-carrageenan chains. The many decades-long debated issue on whether the ordered state can exist as single or double helix, is conclusively resolved by demonstrating the existence of a unimeric helix formed intramolecularly by a single polymer chain.Carrageenans are naturally occurring anionic polysaccharides extracted from red seaweed species and find application in food, cosmetic, and pharmaceutical product formulations where they serve as gelling agents, thickeners, stabilizers, and excipients. [1,2] Referring to a family of sulfated linear galactans, their principal disaccharide repeating unit consists of alternating b-(1!3)-and a-(1!4)-d-galactose or 3,6-anhydride residues. [1c] Following the traditional classification, iotaand lambda-carrageenan have two and three sulfate groups, respectively, with the former containing a 3,6-anhydridebridge. [1a] These chemical and structural varieties combined with the ionic environment control their conformation. [3] The sequence motif of lambda-carrageenan has been suggested to prevent the formation of any secondary structure and thus gel formation, whereas iota-carrageenan has been reported to be capable of undergoing a coil-helix transition as a first event of gelation. [4] For their thermoreversible gelation in aqueous solution, a two-step process involving an initial ion-induced helix formation followed by association into networks is generally accepted. Nonetheless, the mechanisms governing the conformational transition, ion-specificity effects, and the mode of molecular association into a percolating gel are still highly debated. [2] An ordered dimeric double helix with 1.3 nm diameter was initially proposed for iota-carrageenan based on fiber X-ray diffraction results, [5a] which was further supported by osmometry, [5b] stopped-flow polarimetry, [5c] sizeexclusion chromatography combined with light scattering, [5d, e] and differential scanning calorimetry.[5f] Strong indication for a single-stranded iota-carrageenan helix as the ordered conformation emerged, however, from other osmometry studies combined with measurements of optical rotation [4] and intrinsic viscosity, [6a] which were substantiated by light scattering data, [6b] leaving the nature of the ordered state a highly controversial issue.This study focuses on resolving the disorder-order conformational transition in molecular solutions of these anionic polysaccharides by atomic force microscopy (AFM) imaging. The conformational change from disordered carrageenans i...

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Unravelling Secondary Structure Changes on Individual Anionic Polysaccharide Chains by Atomic Force Microscopy

2014

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“…The reported values for K and in the literature were 2.09×10 -4 and 0.78, respectively 136 (Vreeman, Snoeren, & Payens, 1980). The molecular weight (m) for the KC monosaccharide 137 was also considered to be 0.192 kDa.…”

Section: Theoretical Basis: Degradation Rate 111mentioning

confidence: 99%

Kinetic study of κ-carrageenan degradation and its impact on mechanical and structural properties of chitosan/κ-carrageenan film

Shahbazi¹,

Rajabzadeh²,

Ettelaie

et al. 2016

Carbohydrate Polymers

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8The purpose of the current research was to study -carrageenan degradation behavior through 9 thermal treatment, and its influence on chitosan/ -carrageenan film properties. A pseudo first-10 order reaction equation was applied by using reciprocal plots of -carrageenan molecular mass 11 versus heating time, which showed strongly heating time dependence. Incorporation of thermally 12 treated -carrageenan to the chitosan had a deterioration effect on water resistance and water 13 vapor permeability of the blend, in contrast to those for intact. A dramatic decrease of 14 equilibrium moisture content and tensile strength were noticed, in which a longer time was found 15 to be more effective. Furthermore, the contact angle of the films was found to be a function of 16 the heating time. SEM revealed apparent agglomeration of -carrageenan through the thermal 17 process. AFM demonstrated that the intact blend had the most flat surface, whilst the blend 18 containing treated -carrageenan became rugged and uneven with high roughness. 19

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“…The specific viscosity (ηsp) and the Huggins constant (kH) are dimensionless, while the intrinsic viscosity ([η]) and the concentration (c) have the units of mL.g -1 and g.mL -1 , respectively. The value of kH for the κ-carrageenan solution is 0.35 [54].…”

Section: Molecular Weight Determinationmentioning

confidence: 96%

“…The efflux times of the solutions were measured using an Ubbelohde capillary viscometer (type 531 030c SchottGerate, Germany) in a constant temperature at 45.0±0.1 o C. The intrinsic viscosity ([η]) was calculated from the specific viscosity (ηsp). The intrinsic viscosity is the average intercept of Huggins and Kraemer equation [54] in Equation (1).…”

Section: Molecular Weight Determinationmentioning

confidence: 99%

Kinetics of Oxidative Depolymerization of κ-carrageenan by Ozone

Prasetyaningrum

Ratnawati

Jos

2017

Bull. Chem. React. Eng. Catal.

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Depolymerization kinetics of κ-carrageenan by ozone treatment has been studied at various pHs and times. The purified κ-carrageenan with the initial molecular weight of 271 kDa was dispersed in water to form (1 % w/v) solution. Ozone with 80±2 ppm concentration and constant flow rate of 3 L.min -1 was bubbled into the κ-carrageenan solution. The experiments were conducted at pH of 3, 7, and 10 at different times (5, 10, 15, and 20 minutes) of ozonation. The viscosity of the solution was measured using Ubbelohde capillary viscometer, which was then used to find the number-average molecular weight by Mark-Houwink equation. The number-average molecular weight data was treated using zero, first, and the second-order reaction kinetics model, to obtain the kinetics of κ-carrageenan depolymerization. The depolymerization is assumed to occur by random scission. The results show that the kinetics rate constant of κ-carrageenan depolymerization is higher at lower pHs. The second-order model is more suitable for describing the kinetics of depolymerization of κ-carrageenan by ozonation process. The rate constants for the second-order kinetics model are 5.45×10 -4 min -1 , 1.27×10 -4 min -1 , and 7.21×10 -5 min -1 for pH 3, 7, and 10, respectively. The actual values of reaction order under acid and alkali conditions are ranging from 1.88 to 1.90.

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Physicochemical investigation of k‐carrageenan in the random state

Cited by 102 publications

References 34 publications

Unravelling Secondary Structure Changes on Individual Anionic Polysaccharide Chains by Atomic Force Microscopy

Unravelling Secondary Structure Changes on Individual Anionic Polysaccharide Chains by Atomic Force Microscopy

Kinetic study of κ-carrageenan degradation and its impact on mechanical and structural properties of chitosan/κ-carrageenan film

Kinetics of Oxidative Depolymerization of κ-carrageenan by Ozone

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