Equilibrium and Nonequilibrium Association Processes of κ-Carrageenan in Aqueous Salt Solutions

Bongaerts, Karin; Reynaers, Harry; Zanetti, Flavio; Paoletti, Sergio

doi:10.1021/ma981204r

Cited by 30 publications

(55 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Experimental data provide support for a dimeric structure of polysaccharides in an ordered state, and interpretations lead either to duplexes of single helices [13][14][15] or, as forcarrageenan, double helices (intertwined strands) [8,10,16]. The aggregation of agarose molecules in gels also occurs by association of single or double helices [17,18].…”

Section: Introductionmentioning

confidence: 94%

Physical state of κ-carrageenan modulates the mode of action of κ-carrageenase from Pseudoalteromonas carrageenovora

Lemoine

Collén

Helbert

2009

Biochemical Journal

View full text Add to dashboard Cite

Pseudoalteromonas carrageenovora kappa-carrageenase is a glycoside hydrolase involved in the bioconversion of carrageenans. Carrageenans are sulfated galactans that are densely packed in red algal cell walls. Previous crystallographic investigations revealed that the active site of kappa-carrageenase has a tunnel-shaped topology, suggesting a processive mode of action for this enzyme. To biochemically characterize the enzymatic depolymerization of kappa-carrageenan, soluble and solid substrates (in both gel and powder forms) were incubated with P. carrageenovora kappa-carrageenase. The average molecular mass of soluble carrageenan decreased rapidly, and all possible degradation products were observed, suggesting random degradation of kappa-carrageenan. In contrast, as expected for a processive-type carrageenase, the average molecular mass of solid carrageenan decreased very slowly, and tetrasaccharide production was high. Interestingly, experimentally determined processivity was similar for gel and powder, suggesting that, in addition to an adapted catalytic site, the substrate must be in the solid state for kappa-carrageenase processivity to operate, whatever the level of carrageenan ordering.

show abstract

Section: Introductionmentioning

confidence: 94%

Physical state of κ-carrageenan modulates the mode of action of κ-carrageenase from Pseudoalteromonas carrageenovora

Lemoine

Collén

Helbert

2009

Biochemical Journal

View full text Add to dashboard Cite

show abstract

“…Generally, when a polyelectrolyte is in excess, the sequence of phases with an increasing polyelectrolyte concentration involves complexation, phase separation, and gelation. Besides the conformation and flexibility of polymer chains, these processes depend on other factors such as the distance between charges on the polyelectrolyte, intrapolymer hydrophobic effects, and surfactant head group size (13,14).…”

Section: Introductionmentioning

confidence: 99%

Interactions Between Dodecylammonium Chloride and ι-Carrageenan

Tomašić

Filipović-Vinceković

2002

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

“…For higher values of sodium iodide concentration, aggregation does indeed take place, nevertheless, at a reduced extent. 6 The binding of iodide explains why the KC solutions require sodium iodide as a solvent to give a nematic liquid crystalline phase. 4 These solutions show a macroscopic phase separation into one anisotropic bottom phase and one isotropic top phase.…”

mentioning

confidence: 99%

Isotropic−Nematic Phase Equilibrium and Phase Separation of κ-Carrageenan in Aqueous Salt Solution: Experimental and Theoretical Approaches

Chronakis

Ramzi

2002

Biomacromolecules

View full text Add to dashboard Cite

The behavior of chiral-nematic and isotropic phases of helical κ-carrageenan in aqueous solution of sodium iodide was compared with that of the anisotropic biphasic phase that contains both these phases. On the basis of birefringence, rheology, chemical analysis, average molecular weight, and polydispersity index measurements, we derived a number of characteristic differences as well as similarities between these phases, over a range of polysaccharide concentrations obtained by the dilution of each phase. For example, we assessed the critical concentration of an isotropic-anisotropic transition (C i ), the temperature of the anisotropic-isotropic phase shift during thermal heating-cooling cycles, and the viscosity changes due to the phase shift and due to the diminishing of the helical conformation. We also demonstrated how the different phases and their dilutions behave under the effect of shear and frequency of oscillation and how the viscoelastic properties vary in each phase and discussed the isotropic and anisotropic liquid crystal controlling behavior mechanisms. From a theoretical point of view, we propose to combine the wormlike chain model for semiflexible polyelectrolytes interacting via both hard-core and electrostatic repulsion to assess the concentration of isotropic-nematic transition, to assess the coexistence concentration range, and to determine the effects of charge by applying the effective diameter and a twisting effect. IntroductionThe carrageenans are linear, sulfated polygalactans extracted from various species of marine red algae, (i.e., Eucheuma cottoni, Eucheuma spinosum, Gigartina acicularis). 1,2 The primary structure is based on a repeating disaccharide sequence of 1,3-linked -D-galactopyranose and 1,4-linked 3,6-anhydro-D-galactopyranose residues. κ-and ι-carrageenan are the two best known gelling varieties.Rigid and semirigid macromolecules can form gels, but there is also a possibility to form ordered phases (nematic, chiral nematic, smectic, hexatic) or both gels and liquid crystalline phases. 3 The liquid crystalline phase is caused by restrictions on rotation, which in turn are caused by volume exclusion for the polymers of high axial ratios. Most experimental investigations on κ-carrageenan (KC) have dealt with conditions where gel formation or aggregations of the helices occur, therefore preventing the development of longrange liquid crystalline order. However, binding of iodide to the (negatively charged) KC helix increases the charge density, thus preventing aggregation and further gelation of the helices. 4,5 In fact, this was demonstrated for sodium iodide concentration of 0.1 M for polymer concentrations up to about 1 g/L. For higher values of sodium iodide concentration, aggregation does indeed take place, nevertheless, at a reduced extent. 6 The binding of iodide explains why the KC solutions require sodium iodide as a solvent to give a nematic liquid crystalline phase. 4 These solutions show a macroscopic phase separation into one anisotropic bottom phase and one isot...

show abstract

Equilibrium and Nonequilibrium Association Processes of κ-Carrageenan in Aqueous Salt Solutions

Cited by 30 publications

References 9 publications

Physical state of κ-carrageenan modulates the mode of action of κ-carrageenase from Pseudoalteromonas carrageenovora

Physical state of κ-carrageenan modulates the mode of action of κ-carrageenase from Pseudoalteromonas carrageenovora

Interactions Between Dodecylammonium Chloride and ι-Carrageenan

Isotropic−Nematic Phase Equilibrium and Phase Separation of κ-Carrageenan in Aqueous Salt Solution: Experimental and Theoretical Approaches

Contact Info

Product

Resources

About