[Study of functional groups in the active center of alpha-galactosidase of Penicillium sp. 23].

Effect of metal ions and specific chemical reagents (EDTA, sodium aside, o-phenanthroline, n-chlormercurybenzoate, iodacetamide, N-ethylmaleinimide, L-cystein, dithiotreitol, beta-mercaptoethanol) on activity of alpha-galactosidase isolated from the culture liquid of micromycete Penicillium sp. 23 has been studied. It has been established that alpha-galactosidase is not metalloenzyme (lack of the inhibitor effects under treatment of enzyme by EDTA, sodium aside, o-phenanthroline). The heavy metal ions (Ag+ and Hg2+) inhibit the rate of alpha-galactosidase reaction; Ki for Ag+ and Hg2+ ions makes up 3.3 x 10(-5) and 3.0 x 10(-7) M, respectively. It has been established by the inhibitory and kinetic analysis that a group (groups) with ionization constant about 6.0, are in the enzyme active centre which apparently corresponds to histidine imidasole group. The sulfhydryl groups do not take part in catalysis but play the important role in maintaining active conformation of the protein molecule.