Carrageenans structure

Table I. Molecular Repeat Distances and Pitches of Agarose and Carrageenan Structures...

M. W. McLean and F. B. Williamson, Enzymes from Pseudomonas carrageenovora. Application to studies of carrageenan structure, Proc. Int. Seaweed Symp., 10 (1981) 479 484. 

C. W. Greer and W. Yaphe, Enzymatic analysis of carrageenans Structure of carrageenan from Eucheuma nudum, Hydrobiologia, 11(6/117), (1984) 563567. 

H. J. Bixler, K. Johndro, and R. Falshaw, Kappa-2 carrageenan Structure and performance of commercial extracts. II. Performance in two simulated dairy applications, Food Hydrocolloids, 15 (2001) 619-630. 

Sulfated galactans from Schyzimenia binderi are DL-hybrids, with predominance of carrageenan structures devoid of 3,6-anhydrogalactose. Sulfation was found on C-2, C-4, or both positions, on the 3-linked p D-galactose units and on C-3 on the 4-linked a-galactose residues (Matsuhiro, Conte, Damonte, Kolender, Matulewicz, Mejias, Pujol, Zuniga 2005). 

Takano, R., Shiomoto, K., Kamel, K., Hara, S., Hirase, S. (2003). Occurrence of carrageenan structure in an Agar from the red seaweed Digenea simplex (Wulfen) C.Agardh (Rhodomelaceae, Ceramiales) with a short review of carrageenan-agarocolloid hybrid in the Florideophycidae. Botanica Marina, 46, 142-150. 

Consistent with their chemical differences, the molecular structures of i- and K-carrageenans are not identical. A shorter pitch and an offset positioning of the two chains in the kappa helix is compatible with the lack of sulfate group on every 3,6-anhydrogalactose residue. The variations in molecular structures mirror the types of junction zones formed by these polymers and relate to the observed gelation properties. 

Carrageenan has long been considered to be a simple polymer of D-galacto-4-sulfate joined at carbons 1 and 3. While this unit is part of the main structural feature, recent work has disclosed additional fine points. Thus, carrageenan is known to be a mixture of components of varying viscosities and varying sensitivities to potassium. 

Apparently, A-carrageenan is not a simple structure and must have some irregularity in the distribution of its sulfate groups. Also, an occasional side residue may be present. There are still unexplained points about the x-ray spectra of A-carrageenan. 

C. Carrageenan and gellan gum gelation mechanism and supermolecular structure... 

Funami, T., Hiroe, M., Noda, S., Asai, I., Ikeda, S., and Nishinari, K. (2007). Influence of molecular structure imaged with atomic force microscopy on the rheological behavior of carrageenan aqueous system in the presence or absence of cations. Food Hydrocolloids 21, 617-629. 

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