laminarin

Laminarin, also known as laminaran, is a storage beta-glucan polysaccharide found in brown algae (Phaeophyceae). It is composed mainly of β-D-glucose units linked by β-1,3-glycosidic bonds to form a linear backbone, with occasional β-1,6-linked side chains that create branching. The degree of polymerization and branching varies by species and extraction method, yielding molecular weights from a few to several tens of kilodaltons. Laminarin is typically water-soluble under many conditions.

Natural sources of laminarin include common brown seaweeds such as Laminaria, Saccharina, and Fucus species. It serves as an energy reserve in these algae, enabling glucose mobilization when needed. Extraction and isolation methods can influence the resulting polysaccharide’s molecular mass and branching pattern.

In research and biochemistry, laminarin is used as a model beta-glucan and as a substrate for enzymes that degrade beta-1,3-glucans, such as laminarinases and beta-glucosidases. In immunology, beta-glucans including laminarin are studied for interactions with pattern recognition receptors such as dectin-1, which can trigger innate immune responses. Because of its variable structure, laminarin is sometimes employed as a reagent to probe receptor activation or as a competitive ligand in experimental setups.

Applications and notes: laminarin is primarily a laboratory reagent and a source of beta-glucans for enzymatic and immunological studies. Its properties depend on the algal source and preparation, so published results can reflect substantial variation in molecular weight and branching.