O. V. Gudzenko, N. V. Borzova, L. D. Varbanets
The effect of cations, anions and specific chemical reagents: 1-[3-(dimethylamino)propyl]-3-ethylcarbodiіmide methiodide, ЕDТА, о-phenanthroline, dithiotreitol, L-cysteine, ?-mercaptoethanol, p-chlormercurybenzoate (p-ChMB), N-ethylmaleimide on the activity of ?-L-rhamnosidase of Eupenicillium erubescens has been investigated. The essential role of Ag+ and Hg2+ which inhibit the ?-L-rhamnosidase activity by 47-73% has been shown. Whereas L-cysteine exhibits the protective effect, rhamnose in concentration of 1–5 mM does not protect the enzyme from negative effect of Ag+ and Hg2+. Basing on the inhibitory and kinetic analysis it was supposed that the carboxyl group of C-terminal aminoacid and imidazole group of histidine take part in the catalytic action of ?-L-rhamnosidase. It was assumed that sulphydryl groups took part in catalysis, carried out by ?-L-rhamnosidase of E. erubescens, since the activity of ?-L-rhamnosidase inhibited by p-ChMB and thiol reagents such as dithiothreitol, L-cysteine, ?-mercaptoethanol did not remove its inhibitory action.
Key words: ?-L-rhamnosidase, Eupenicillium erubescens, metal ions, specific chemical reagents.
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