V. V. Sova

Structure, biological activity, and enzymatic transformation of fucoidans from the brown seaweeds.

Recent advances in the study of fucoidans, biologically active sulfated α‐L‐fucans of diverse structures and synthesized exclusively by marine organisms, are overviewed. Their structure, biological activity, the products of their enzymatic degradation and the different enzymes of degradation and modification are considered.

Distribution of O-glycosylhydrolases in marine invertebrates. Enzymes of the marine mollusk Littorina kurila that catalyze fucoidan transformation

The distribution of O-glycosylhydrolases (fucoidan hydrolases, α-D-mannosidases, β-D-glucosidases, and β-D-galactosidases) in 30 species of marine invertebrates occurring in the Sea of Japan was studied. It is shown that fucoidanases and glycosidases are widespread in the animals analyzed. Some molluscan, annelid, and echinoderm species can probably serve as objects for isolation and detailed study of the fucoidan-hydrolyzing enzymes. Fucoidan hydrolase, α-L-fucosidase, and arylsulfatase from the marine mollusk Littorina kurila were isolated and described. It was found that α-L-fucosidase and arylsulfatase hydrolyze synthetic substrates and cannot hydrolyze natural fucoidan, whereas fucoidan hydrolase cleaves fucoidan to produce sulfated oligosaccharides and fucose.

Filamentous Marine Fungi as Producers of O-Glycosylhydrolases : β-1, 3-Glucanase from Chaetomium indicum

Ninety fungal strains (42 species) isolated from marine habitats were studied for their ability to produce extracellular enzymes. Cultural filtrates of these strains were shown to contain a series of glycosidases (β-glucosidases, N-acetyl-β-glucosaminidases, β-galactosidases α-mannosidases) and glucanases (1,3-β-glucanases, amylases) which varied with habitat. The level of activity depended on the species of fungi. Several promising strains capable of producing both individual enzymes and a set of enzymes for splitting carbohydrate-containing compound have been isolated. Optimal conditions for growth of Chaetomium indicum and for biosynthesis of β-1,3-glucanase were determined. β-1,3-Glucanase was isolated using ion-exchange chromatography, ultrafiltration, and gel filtration. The presence of 2 enzyme forms was shown; both forms were exo-β-1,3-glucanases.

Catalytic properties and mode of action of endo-(1→3)-β-d-glucanase and β-d-glucosidase from the marine mollusk Littorina kurila

A complex of the enzymes from the liver of the marine mollusk Littorina kurila that hydrolyzes laminaran was investigated. Two (1-->3)-beta-d-glucanases (G-I and G-II) were isolated. The molecular mass of G-I as estimated by gel-permeation chromatography and SDS-PAGE analysis was 32 and 40kDa, respectively. The G-II molecular mass according to SDS-PAGE analysis was about 200kDa. The pH optimum for both G-I and G-II was pH 5.4. The G-I had narrow substrate specificity and hydrolyzed only the (1-->3)-beta-d-glucosidic bonds in the mixed (1-->3),(1-->6)- and (1-->3),(1-->4)-beta-d-glucans down to glucose and glucooligosaccharides. This enzyme acted with retention of the anomeric configuration and catalyzed a transglycosylation reaction. G-I was classified as the glucan endo-(1-->3)-beta-d-glucosidase (EC 3.2.1.39). G-II exhibited both exo-glucanase and beta-d-glucoside activities. This enzyme released from the laminaran glucose as a single product, but retained the anomeric center configuration and possessed transglycosylation activity. The hydrolysis rate of glucooligosaccharides by G-I decreased with an increase of the substrates degree of polymerization. In addition to (1-->3)-beta-d-glucanase activity, the enzyme had the ability to hydrolyze p-nitrophenyl beta-d-glucoside and beta-d-glucobioses: laminaribiose, gentiobiose, and cellobiose, with the rate ratio of 50:12:1. G-II may correspond to beta-d-glucoside glucohydrolase (EC 3.2.1.21).

Distribution of O-glycosylhydrolases in marine fungi of the Sea of Japan and the Sea of Okhotsk: Characterization of exocellular N-acetyl-β-D-glucosaminidase of the marine fungus Penicillium canescens

The capacity to produce exocellular enzymes was studied for 92 samples of fungi from various marine habitats in the Sea of Okhotsk (78 strains) and the Sea of Japan (14 strains). Strains producing highly active glycanases and glycosidases were found. Synthesis of O-glycosylhydrolases was stimulated by addition of laminaran to the nutrient medium. Highly purified N-acetyl-β-D-glucosaminidase was isolated from the marine fungus Penicillium canescens. The molecular weight of the enzyme determined by SDS-Na-electrophoresis was 68 kDa. The enzyme displayed maximum activity at pH 4.5 and temperature 45°C. Inactivation half-time of the enzyme at 50°C was 25 min. N-acetyl-β-D-glucosaminidase hydrolyzed both β-glucosaminide and β-galactosaminide bonds and possessed a high transglycosylating activity.

Extracellular β-D-glucosidase of the Penicillium canescens marine fungus

Extracellular β-D-glucosidase was isolated in a homogeneous state from the Penicillium canescens marine fungus. According to SDS-electrophoresis, the molecular weight of the enzyme was 64 kDa and the maximal activity was observed at pH 5.2 and 70°C. Glucosidase catalyzed the hydrolysis of β-glycosidic bonds both in glycosides and in glucose disaccharides and had transglycosylation activity. The enzyme can be used for the deglycosylation of natural glycosides and in enzymatic synthesis of new carbohydrate—containing compounds.

Glycosidases of marine organisms

This review discusses the catalytic properties, activity regulation, structure, and functions of O-glycoside hydrolases from marine organisms exemplified by endo-1→3-β-D-glucanases of marine invertebrates.

A comparative study of the specificity of fucoidanases of marine microorganisms and invertebrates.

Fucoidans, high-sulfated polysaccharides of brown algae, exhibit a broad range of biological activity. Anticoagulation and antiviral effects (including effects against HIV, the hepatitis virus, and the herpes simplex virus) are of the greatest interest [1–3]. The structure– function correlation in these polysaccharides remains virtually unknown. Because the molecular weight of fucoidans is rather high, they should be depolymerized to be used as pharmacological preparations.

β-1,3-Glucanase from Unfertilized Eggs of the Sea Urchin Strongylocentrotus intermedius. Comparison with β-1,3-Glucanases of Marine and Terrestrial Mollusks

Abstractβ-1,3-Glucanase (Lu) was isolated from unfertilized eggs of the sea urchin Strongylocentrotus intermedius. A comparative study of some properties of β-1,3-glucanase Lu and β-1,3-glucanases with different action types—endo-β-1,3-glucanase from crystalline style of the marine mollusk Spisula sachalinensis (LIV) and exo-β-1,3-glucanase from the terrestrial snail Eulota maakii (LII)—was performed. It was found that β-1,3-glucanase Lu hydrolyzes laminaran with a high yield of glucose in the reaction products. The enzyme hydrolyzes substrates with retention of the glycosidic bond configuration, is able to cleave modified substrates, and exhibits transglycosylating activity. All properties of β-1,3-glucanase from S. intermedius were more similar to those of the endo-β-1,3-glucanase from the marine mollusk (LIV) than exo-β-1,3-glucanase LII from the terrestrial snail. The differences in the effect of LIV and Lu on laminaran are probably related to the functions of β-1,3-glucanase Lu from sea urchin eggs (which, in contrast to LIV, is not a digestive enzyme).

O-Glycosylhydrolases of Marine Filamentous Fungi: β-1,3-Glucanases of Trichoderma aureviride

The ability to produce extracellular O-glycosylhydrolases was studied in 14 strains of marine filamentous fungi sampled from the bottom sediments of the South China Sea. The following activities were detected in the culture liquids of the fungi: N-acetyl-β-D-glucosaminidase, β-D-glucosidase, β-D-galactosidase, β-1,3-glucanase, amylase, and pustulanase. β-1,3-Glucanases were isolated by ultrafiltration, hydrophobic interaction chromatography, and ion exchange chromatography, and their properties were studied. Data on products of enzymatic digestion of laminaran, absence of transglycosylation activity, and the pattern of action of natural inhibitors confirmed that β-1,3-glucanase belonged to the exo type. Inhibitor analysis demonstrated the role of a thiol group and tryptophan and tyrosine residues in the catalytic activity.