[Influence of metal ions and specific chemical reagents on activity of alpha-L-rhamnosidase of Eupenicillium erubescens].

The effect of cations, anions and specific chemical reagents: 1-[3-(dimethylamino) propyl]-3-ethylcarbodiimide methiodide, EDTA, o-phenanthroline, dithiotreitol, L-cysteine, beta-mercaptoethanol, p-chlormercurybenzoate (p-ChMB), N-ethylmaleimide on the activity of alpha-L-rhamnosidase of Eupenicillium erubescens has been investigated. The essential role of Ag+ and Hg2+ which inhibit the alpha-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 alpha-L-rhamnosidase. It was assumed that sulphydryl groups took part in catalysis, carried out by alpha-L-rhamnosidase of E. erubescens, since the activity of alpha-L-rhamnosidase inhibited by p-ChMB and thiol reagents such as dithiothreitol, L-cysteine, beta-mercaptoethanol did not remove its inhibitory action.