Some Enzymatic Properties of Polymannuronic Acid 5-Epimerase in Brown Algae

Ishikawa, M.; Nisizawa, Kazutosi

doi:10.1515/9783110865271-052

Cited by 3 publications

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“…A key enzyme in the biosynthesis of alginate is the mannuronan C-5 epimerase responsible for the C-5 epimerization of D-mannuronic acid into L-guluronic acid. This enzyme has been isolated, and partly characterized, from the bacterium Azotobacter vinelandii Gorin & Spencer, 1966), and its presence has been reported in a wide range of algae (Hellebust & Haug, 1972;Madgwick etal., 1978;Ishikawa & Nisizawa, 1981;Shiariwa et al, 1975). Aside from the small amounts present, there are two specific problems establishing the presence of an enzyme in cells of brown algae: The inhibitory effect of the polyphenols, and the copious amounts of alginate coextracted from the cell wall and the intercellular matrix.…”

Section: Introductionmentioning

confidence: 99%

Mannuronan C-5 epimerase activity in protoplasts of Laminaria digitata

1993

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Biosynthesis of alginate in algae may be studied by following the cell wall regeneration of brown seaweed protoplasts in culture. The enzyme mannuronan C-5 epimerase will control the composition of the alginate being synthetized.Freshly isolated protoplasts from the thallus of young Laminaria digitata plants showed only low expression of this enzyme. However, after prolonged periods in culture, this activity increased 15-fold. The synthesis of C-5 epimerase by the protoplasts is probably essential for the formation of a new cell wall.After cellular disruption by osmotic shock and centrifugation, most of the epimerase activity resided in the pellet fraction. This may indicate that the enzyme is membrane associated.

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Section: Introductionmentioning

confidence: 99%

Mannuronan C-5 epimerase activity in protoplasts of Laminaria digitata

1993

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“…The inherently high viscosities encountered in reactor growth limit oxygen transport and lead to poor productivity. The enzymes of alginate modification have also been located and partially purified in the brown marine algae (Madgwick et al 1973a, b, 1978, Shiraiwa et al 1975, Ishikawa and Nisizawa 1981. The biotechnical objective of the current research programm, is, therefore, to derive these enzymes directly from the alginate forming algae.…”

Section: Introductionmentioning

confidence: 99%

Alginate-modifying Enzymes in Australian Marine Algae

Greene¹,

Madgwick²

1986

Botm

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Twelve Australian marine algae from Sydney coastal waters, Ecklonia radiata, Hormosira banksii, a species of Sargassum, a species of Cystophora, Padinafraseri, Dictoyota dichotoma, Endarachne binghamiae, Splanchnidium rugosum, Colpomenia sinuosa and C. peregrina, Acinetospora crinata and a species of Zonaria were tested for alginate lyase and alginate epimerase activity. Easily soluble protein (ca 140 mg/kg wet algae) was prepared from acetone powders (3-15% of wet algae) at low temperatures (ca 0 °C) in tris(hydroxymethyl)aminomethane HC1 buffer (pH 7.8) containing 4% (w/v) polyvinylpyrolidone, 1.5 ΙΉΜ dithiothreitol and 200 mM NaCl. A species of Zonaria, Ecklonia radiata and Acinetospora crinata had highest lyase activity while the Zonaria species, the two Colpomenia species and A. crinata had highest epimerase activity. There were significant variations in enzyme activity between species, seasons and tissues. A 2 -8 fold purification was found for the epimerase from a single ammonium sulphate precipitation but the lyase gave only a l -3 fold improvement. Partial acid hydrolysis demonstrated that epimerised low mannuronic acid alginate gave ten to twenty per cent conversion to guluronic acid and the mannuronic/guluronic acid mixed segments showed the greatest degree of epimerisation.

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Alginate‐modifying enzymes

Gacesa¹

1987

FEBS Letters

185

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Some Enzymatic Properties of Polymannuronic Acid 5-Epimerase in Brown Algae

Cited by 3 publications

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Mannuronan C-5 epimerase activity in protoplasts of Laminaria digitata

Mannuronan C-5 epimerase activity in protoplasts of Laminaria digitata

Alginate-modifying Enzymes in Australian Marine Algae

Alginate‐modifying enzymes

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