Isolation and characterization of two types of β-1,3-glucanases from the common sea hare Aplysia kurodai

Abstract

Two types of β-1,3-glucanases, AkLam36 and AkLam33 with the molecular masses of 36 kDa and 33 kDa, respectively, were isolated from the digestive fluid of the common sea hare Aplysia kurodai. AkLam36 was regarded as an endolytic enzyme (EC 3.2.1.6) degrading laminarin and laminarioligosaccharides to laminaritriose, laminaribiose, and glucose, while AkLam33 was regarded as an exolytic enzyme (EC 3.2.1.58) directly producing glucose from polymer laminarin. AkLam36 showed higher activity toward β-1,3-glucans with a few β-1,6-linked glucose branches such as Laminaria digitata laminarin (LLam) than highly branched β-1,3-glucans such as Eisenia bicyclis laminarin (ELam). AkLam33 showed moderate activity toward both ELam and LLam and high activity toward smaller substrates such as laminaritetraose and laminaritriose.Although both enzymes did not degrade laminaribiose as a sole substrate, they were capable of degrading it via transglycosylation reaction with laminaritriose. The N-terminal amino-acid sequences of AkLam36 and AkLam33 indicated that both enzymes belong to the glycosyl hydrolase family 16 like other molluscan β-1,3-glucanases.3

An endo-β-1,4-mannanase, AkMan, from the common sea hare Aplysia kurodai

“…Biochemical properties of sea hare mannosidase will be published elsewhere. On the other hand, we have reported various kinds of molluscan polysaccharidedegrading enzymes, e.g., alginate lyase, cellulase, and -1,3-glucanase (Shimizu et al, 2003;Suzuki et al, 2003;Suzuki et al, 2006;Hata et al, 2009;Kumagai and Ojima, 2010). Studies on these enzymes are expected to provide us the useful information about the degradation process of seaweeds' polysaccharides, which are expected as functional polysaccharides for human and a potential biomass in future.…”

“…In addition, many animals are available in the shore of Hakodate, Hokkaido, in breeding season (June -July). Indeed, we recently succeeded to isolate -1,3-glucanase, a laminarin-degrading enzyme, from the digestive fluid of A. kurodai (Kumagai and Ojima, 2010).…”

The Genome of the Alga-Associated Marine Flavobacterium Formosa agariphila KMM 3901 T Reveals a Broad Potential for Degradation of Algal Polysaccharides

“…An ␣-amylase (GH13) and three ␣-glucosidases (GH31) indicate the capacity for ␣-1,4-glucan degradation. Degradation of the ␤-1,3-glucan laminarin is indicated by an endo-␤-1,3-glucanase (GH16) (53). Mannan can likely be degraded via an endo-␤-1,4-mannosidase (GH26) and ␤-glucosidases (GH3) (54).…”

Characterization of a β-D-mannosidase from a marine gastropod, Aplysia kurodai

“…A. kurodai is known as a typical herbivorous marine mollusk which possesses various kinds 5 of polysaccharide-degrading enzymes, e.g., alginate lyase laminarinase (Kumagai and Ojima, 2010) in addition to -mannanase (Zahura et al, 2010 and.…”