Proteins of Brown Seaweeds as Inhibitors of Endo-1-->3-beta-D-glucanases of Marine Invertebrates

S. P. Ermakova¹, Yu. V. Burtseva¹, V. V. Sova¹, V. V. Kratchun², and T. N. Zvyagintseva^1*

¹Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Sciences, pr. 100-letiya Vladivostoka 159, Vladivostok, 690022 Russia; fax: (4232) 31-4050; E-mail: piboc@stl.ru (subject: to Zvyagintseva)

²Far Eastern State University, Vladivostok, 690000 Russia

^* To whom correspondence should be addressed.

Received March 27, 2000; Revision received June 1, 2000

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It has been found that aqueous-ethanol extracts of brown seaweeds contain substances inhibiting endo-1-->3-beta-D-glucanases, the digestive enzymes of marine mollusks. The inhibitors were detected in 14 of 21 brown seaweeds investigated. An irreversible protein inhibitor possessing high specificity toward endo-1-->3-beta-D-glucanases of marine mollusks was isolated from the brown seaweed Laminaria cichorioides. As determined by gel filtration, the molecular mass of the inhibitor is 46 kD. The value of [I]₅₀ (10^-8 M) for the inhibitor is comparable with the corresponding value for natural inhibitors of amylases from terrestrial plants. The results of chemical modification indicated that tryptophan, glutamic acid, aspartic acid, histidine, and probably tyrosine residues are important for the interaction of the inhibitor with the enzyme.

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KEY WORDS: brown seaweeds, Laminaria cichorioides, endo-1-->3-beta-D-glucanase, amylase, protein inhibitor, glutamic acid

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