Subunit of a typical mannan showing four 1,4-linked beta-D-mannose units, one with a galactose side chain.
Mannans arepolymers containing the sugarmannose as a principal component.[1][2]They are a type ofpolysaccharide found inhemicellulose, a major source of biomass found in higher plants such as softwoods. These polymers also typically contain two other sugars,galactose andglucose. They are often branched (unlike cellulose).
Yeast have a different type of glucomannan in their cell wall, with a α(1-6) linked backbone and α(1-2) and α(1-3) linkedglucose branches, which may also containphosphodiester bonds.[5] Enzymatic digestion or acid catalysis can help solubilize the glucomannan.[6] It is serologically similar to structures found on mammalian glycoproteins. Detection of mannan leads to lysis in themannan-binding lectin pathway.[citation needed]
The degradation of mannans (and many related forms of hemicellulose) has been well studied. The hydrolysis of the main mannan backbone is catalyzed by various enzymes including β-mannosidase, β-glucosidase, and β-mannase. The side chains are degraded byesterases and α-galactosidase.[1]
When a long chain of mannan ishydrolyzed into shorter chains, these smaller molecules are known asmannanoligosaccharide (MOS). MOS by definition can be produced from either insoluble galactomannan or soluble glucomannan, although the latter type is more widely marketed.[9]
Glucomannan MOS is used as prebiotics in animal husbandry and nutritional supplements due to its bioactivity.[citation needed]
^abMoreira, L. R. S.; Filho, E. X. F. (2008). "An overview of mannan structure and mannan-degrading enzyme systems".Applied Microbiology and Biotechnology.79 (2):165–178.doi:10.1007/s00253-008-1423-4.PMID18385995.S2CID9746196.
^Ye S, Zongo AW, Shah BR, Li J, Li B (2021). "Konjac Glucomannan (KGM), Deacetylated KGM (Da-KGM), and Degraded KGM Derivatives: A Special Focus on Colloidal Nutrition".Journal of Agricultural and Food Chemistry.69 (44):12921–12932.doi:10.1021/acs.jafc.1c03647.
^Kurt A, Kahyaoglu T (2017). "Purification of glucomannan from salep: Part 1. Detailed rheological characteristics".Carbohydrate Polymers.168:138–146.doi:10.1016/j.carbpol.2017.03.060.
^Samuel G, Reeves P (2003). "Biosynthesis of O-antigens: genes and pathways involved in nucleotide sugar precursor synthesis and O-antigen assembly".Carbohydrate Research.338 (23):2503–19.doi:10.1016/j.carres.2003.07.009.PMID14670712.
