1. Structure and rheology of the polysaccharides from Schizymenia dubyi: Isolation of an unusual glucurono-carrageenan.
- Author
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Benech-Arnold T, Navarro DA, Rodríguez C, Schmidt W, Fredericq S, Rojas AM, and Stortz CA
- Subjects
- Viscosity, Polysaccharides chemistry, Polysaccharides isolation & purification, Galactans chemistry, Rhodophyta chemistry, Magnetic Resonance Spectroscopy, Carrageenan chemistry, Rheology
- Abstract
The system of polysaccharides from Schizymenia dubyi (Nemastomatales) was investigated. It contains a mixture of hybrid dl galactans (SH-S) and carrageenan-like polysaccharides, which were separated by means of precipitation with KCl at high concentrations. The structural features of the carrageenan-like fraction (SH-I) were investigated by methylation analysis, desulfation, uronic acid reduction, and NMR spectroscopy. It was concluded that the structure has the typical alternance α-(1 → 3), β-(1 → 4) of d-galactose units, with most of the 3-linked units sulfated in O-2 (and some in O-4), and most of the 4-linked units sulfated in O-3, and substituted in O-2 by single stubs of β-d-glucuronic acid (partly sulfated in each of the three available positions). This substituent has been only seldom found in red seaweed galactans. Rheological studies of 5 % and 10 % w/v SH, SH-S and SH-I aqueous systems, either without ions, or in KCl or CaCl
2 solution gave thickening behaviors. Their random coil conformations justify the pseudoplastic behavior observed in the viscosity versus shear rate curves. As SH-S and SH-I are both contained in SH, an interpenetrating network could form in SH between the glucurono-carrageenan and the agaran, as inferred from the mechanical spectra recorded in water, especially with potassium ion., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Carlos Stortz reports financial support and administrative support were provided by University of Buenos Aires. Carlos A. Stortz reports a relationship with University of Buenos Aires that includes: employment, funding grants, and non-financial support. No conflict of interest If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2024
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