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Structural Diversity in Galactans From Red Seaweeds and Its Influence on Rheological Properties.
Front Plant Sci. 2020; 11:559986.FP

Abstract

Galactans are important components of many plant cell walls. Besides, they are the major polysaccharides in extracellular matrixes from different seaweeds, and other marine organisms, which have an acidic character due to the presence of sulfate groups in their structures. In particular, most of the red seaweeds biosynthesize sulfated galactans with very special linear backbones, constituted by alternating (1→3)-β-d-galactopyranose units (A-unit) and (1→4)-α-galactopyranose residues (B-unit). In the industrially significant seaweeds as source of hydrocolloids, B-units belong either to the d-series and they produce carrageenans (as in the order Gigartinales), or to the l-series, and they are sources of agarose and/or structurally related polymers (i.e., Gelidiales, Gracilariales). In both cases, the latter units appear as cyclized 3,6-anhydro-α-galactose in certain amounts, which can be increased by alkaline cyclization of α-galactose 6-sulfate units. Besides, it has been clearly shown that some red algae produce different amounts of both galactan structures, known as d/l-hybrids. It is not yet clear if they comprise both diasteromeric types of units in the same molecule, or if they are mixtures of carrageenans and agarans that are very difficult to separate. It has been reported that the biosynthesis of these galactans, showing that the nucleotide transport for d-galactopyranose units is UDP-d-Gal, while for l-galactose, it is GDP-l-Gal, so, there is a different pathway in the biosynthesis of agarans. However, at least in those seaweeds that produce carrageenans as major galactans, but also agarans, both synthetic pathways should coexist. Another interesting characteristic of these galactans is the important variation in the sulfation patterns, which modulate their physical behavior in aqueous solutions. Although the most common carrageenans are of the κ/ι- and λ-types (with A-units sulfated at the 4- and 2-positions, respectively) and usually in agarans, when sulfated, is at the 6-position, many other sulfate arrangements have been reported, greatly influencing the functional properties of the corresponding galactans. Other substituents can modify their structures, as methyl ethers, pyruvic acid ketals, acetates, and single stubs of xylose or other monosaccharides. It has been shown that structural heterogeneity at some extent is essential for the proper functional performance of red algal galactans.

Authors+Show Affiliations

Universidad de Buenos Aires, Facultad de Agronomía, Departamento de Biología Aplicada y Alimentos, Cátedra de Química de Biomoléculas (CIHIDECAR,CONICET-UBA), Buenos Aires, Argentina.Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Centro de Investigación de Hidratos de Carbono (CIHIDECAR), Buenos Aires, Argentina. Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, Argentina.Tallinn University, School of Natural Sciences and Health, Tallinn, Estonia.

Pub Type(s)

Journal Article
Review

Language

eng

PubMed ID

33013979

Citation

Ciancia, Marina, et al. "Structural Diversity in Galactans From Red Seaweeds and Its Influence On Rheological Properties." Frontiers in Plant Science, vol. 11, 2020, p. 559986.
Ciancia M, Matulewicz MC, Tuvikene R. Structural Diversity in Galactans From Red Seaweeds and Its Influence on Rheological Properties. Front Plant Sci. 2020;11:559986.
Ciancia, M., Matulewicz, M. C., & Tuvikene, R. (2020). Structural Diversity in Galactans From Red Seaweeds and Its Influence on Rheological Properties. Frontiers in Plant Science, 11, 559986. https://doi.org/10.3389/fpls.2020.559986
Ciancia M, Matulewicz MC, Tuvikene R. Structural Diversity in Galactans From Red Seaweeds and Its Influence On Rheological Properties. Front Plant Sci. 2020;11:559986. PubMed PMID: 33013979.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Structural Diversity in Galactans From Red Seaweeds and Its Influence on Rheological Properties. AU - Ciancia,Marina, AU - Matulewicz,María Cristina, AU - Tuvikene,Rando, Y1 - 2020/09/10/ PY - 2020/06/10/received PY - 2020/08/21/accepted PY - 2020/10/5/entrez PY - 2020/10/6/pubmed PY - 2020/10/6/medline KW - agaran KW - agarose KW - carrageenans KW - polysaccharide structure KW - red seaweeds KW - rheological properties KW - sulfated galactans SP - 559986 EP - 559986 JF - Frontiers in plant science JO - Front Plant Sci VL - 11 N2 - Galactans are important components of many plant cell walls. Besides, they are the major polysaccharides in extracellular matrixes from different seaweeds, and other marine organisms, which have an acidic character due to the presence of sulfate groups in their structures. In particular, most of the red seaweeds biosynthesize sulfated galactans with very special linear backbones, constituted by alternating (1→3)-β-d-galactopyranose units (A-unit) and (1→4)-α-galactopyranose residues (B-unit). In the industrially significant seaweeds as source of hydrocolloids, B-units belong either to the d-series and they produce carrageenans (as in the order Gigartinales), or to the l-series, and they are sources of agarose and/or structurally related polymers (i.e., Gelidiales, Gracilariales). In both cases, the latter units appear as cyclized 3,6-anhydro-α-galactose in certain amounts, which can be increased by alkaline cyclization of α-galactose 6-sulfate units. Besides, it has been clearly shown that some red algae produce different amounts of both galactan structures, known as d/l-hybrids. It is not yet clear if they comprise both diasteromeric types of units in the same molecule, or if they are mixtures of carrageenans and agarans that are very difficult to separate. It has been reported that the biosynthesis of these galactans, showing that the nucleotide transport for d-galactopyranose units is UDP-d-Gal, while for l-galactose, it is GDP-l-Gal, so, there is a different pathway in the biosynthesis of agarans. However, at least in those seaweeds that produce carrageenans as major galactans, but also agarans, both synthetic pathways should coexist. Another interesting characteristic of these galactans is the important variation in the sulfation patterns, which modulate their physical behavior in aqueous solutions. Although the most common carrageenans are of the κ/ι- and λ-types (with A-units sulfated at the 4- and 2-positions, respectively) and usually in agarans, when sulfated, is at the 6-position, many other sulfate arrangements have been reported, greatly influencing the functional properties of the corresponding galactans. Other substituents can modify their structures, as methyl ethers, pyruvic acid ketals, acetates, and single stubs of xylose or other monosaccharides. It has been shown that structural heterogeneity at some extent is essential for the proper functional performance of red algal galactans. SN - 1664-462X UR - https://www.unboundmedicine.com/medline/citation/33013979/Structural_Diversity_in_Galactans_From_Red_Seaweeds_and_Its_Influence_on_Rheological_Properties_ L2 - https://doi.org/10.3389/fpls.2020.559986 DB - PRIME DP - Unbound Medicine ER -
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