Porphyran

Sulfated carbohydrate polymer

Not to be confused with Porphyrin.

Porphyran is a sulfated carbohydrate derived from red algae of the genus Porphyra.[1]

## Composition

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Porphyran is a complex sulfated carbohydrate. It is a highly substituted complex carbohydrate related to agarose with a linear backbone consisting of 3-linked beta-D-galactosyl units alternating with either 4-linked alpha-L-galactosyl 6-sulfate or 3,6-anhydro-alpha-L-galactosyl units. The composition includes 6-O-sulfated L-galactose, 6-O-methylated D-galactose, L-galactose, 3,6-anhydro-L-galactose, 6-O-methyl D-galactose and ester sulfate. Some of the ester is present as 1-4-linked L-galactose 6-sulfate.[1][2][3][4] The precise composition of porphyran shows seasonal and environmental variations.[1] In Porphyra haitanensis, the L-residues are mainly composed of alpha-L-galactosyl 6-sulfate units, and the 3,6-anhydro-galactosyl units are minor.[3] In Porphyra capensis, the ratio of alpha-L-galactose-6-sulfate and the 3,6-anhydrogalactose is 1.2:1.[4] Porphyran is converted to agarose by cyclization of L-galactose-6-sulfate to 3,6-anhydro-L-galactose.

## See also

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* Fucoidan
* Agarose

## References

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1. ^ a b c Rees DA, Conway E (August 1962). "The structure and biosynthesis of porphyran: a comparison of some samples". Biochem. J. 84 (2): 411–6\. doi:10.1042/bj0840411. PMC 1243684. PMID 14490986.
2. ^ Peat S, Turvey JR, Rees DA (August 1961). "Carbohydrates of the red alga, Porphyra umbilicalis". J. Chem. Soc.: 1590–5\. doi:10.1039/jr9610001590.
3. ^ a b Zhang Q, Li N, Liu X, Zhao Z, Li Z, Xu Z (January 2004). "The structure of a sulfated galactan from Porphyra haitanensis and its in vivo antioxidant activity". Carbohydr. Res. 339 (1): 105–11\. doi:10.1016/j.carres.2003.09.015. PMID 14659676.
4. ^ a b Zhang Q, Qi H, Zhao T, et al. (October 2005). "Chemical characteristics of a polysaccharide from Porphyra capensis (Rhodophyta)". Carbohydr. Res. 340 (15): 2447–50\. doi:10.1016/j.carres.2005.08.009. PMID 16150429.