O. V. Gudzenko, N. V. Borzova, L. D. Varbanets

Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kyiv;
e-mail: varbanets@serv.imv.kiev.uа

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

Keywords: Eupenicillium erubescens, metal ions, specific chemical reagents, α-L-rhamnosidase