[Study of functional groups in the active center of alpha-galactosidase of Penicillium sp. 23]. / Issledovanie funktsional'nykh grupp v aktivnom tsentre alpha-galaktozidazy 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.

[Functional groups in the alpha-galactosidase active site in Cladosporium cladosporioides]. / Issledovanie funktsional'nykh grupp v aktivnom tsentre alpha-galaktozidazy Cladosporium cladosporioides.

The activity of alpha-galactosidase isolated from culture fluid of micromycete Cladosporium cladosporioides (Fres.) de Vries 16,038 has been studied as affected by cations, anions and specific chemical reagents (p-chlormercurybenzoate (p-ChMB), iodacetamide, N-ethylmaleimide, L-cysteine, dithiotreitol, beta-mercaptoethanol, EDTA, o-phenanthroline, sodium azide). It has been established that Ag+ ions inhibited competitively alpha-galactosidase at pH 4.0 and 6.0, the inhibition constants (Ki) made 3.6 x 10(-5) M and 4.3 x 10(-6) M, respectively. Galactose in concentration of 1 mM to 5 mM preserved the enzyme from the negative effect of Ag+ ions, while L-cysteine did not manifest the protective effect. Ions of Hg2+ p-ChMB inhibited noncompetitively the activity of alpha-galactosidase, Ki for Hg2+ and p-ChMB made 5.7 x 10(-7) M and 4.7 x 10(-6) M, respectively. Preincubation with galactose does not preserve alpha-galactosidase from the inhibiting effect of Ag+ and p-ChMB, but th[not readable: see text] compounds (L-cysteine, dithiotreitol, beta-mercaptoethanol) restore the enzyme activity. Participation of histidine imidazole group in the catalytic action is supposed on the basis of the inhibitory and kinetic analysis. Sulphydryl groups do not take part in the catalysis but play an important role in supporting the active conformation of the protein molecule. The groups containing the atoms of metals are absent in the alpha-galactosidase molecule.

[The mitogenic properties of Fusarium graminearum and Rhodococcus erythropolis enzymes]. / Mitogennye svoistva fermentov Fusarium graminearum i Rhodococcus erythropolis.

Blast transformation of peripheral blood lymphocytes in healthy people is studied by enzymes of the microbic origin possessing the lectin activity. Galactose oxidase of Fusarium graminearum IMV-F-1060 is shown to be mitogenically active with respect to the lymphocytes in the culture in vitro and may be one of home sources of lymphocytic mitogens for the laboratory investigations.

[The effect of potassium ferricyanide and copper (II) ions on the properties of immobilized galactose oxidase]. / Vliianie ferritsianida kaliia i ionov medi (II) na svoistva immobilizovannoi galaktozooksodazy.

Preparations of galactosooxidase (EC 1.1.3.9) immobilized by activated aminorganosilica have been used to study potassium ferricyanide and bivalent copper ions on the enzyme activity and stability in continuous reactor under pulse conditions. Introduction of potassium ferricyanide is shown to activate the enzyme and inconsiderably affecting its stability with the substrate absent and inducing inactivation of galactosooxidase in the process of catalytic reaction. Cu2+ ions, exerting no effect on the activity of immobilized galactosooxidase, evoke the enzyme inactivation in the process of catalysis.

[Various properties of galactose oxidase from Fusarium graminearum IMV-F-1060 immobilized on aminoorganosilochromes]. / Nekotorye svoistva galaktozooksidazy iz Fusarium graminearum IMB-F-No. 1060, immobilizovannoi na aminoorganosilokhromakh.

Galactose oxidase preparations are obtained from Fusarium graminearum IMV-F-N 1060 immobilized on aminoorganosilochromes activated by cyanuron chloride and 2.4-toluylene diizocyanate. The immobilized preparations were studied for their selective action on different carbohydrate substrates and for the pH-medium dependence of the obtained preparation activity. Potassium ferricyanide is established to have an activating effect on the immobilized enzyme. It is shown that the immobilized galactose oxidase preparations may be used for the analysis of galactose and lactose.

[Properties of Fusarium graminearum galactose oxidase]. / Nekotorye svoistva galaktozooksidazy Fusarium graminearum.

The kinetics and action mechanism of the galactose oxidase from Fusarium graminearum were studied. pH-optimum of the enzyme activity and stability was 7.0, the activity and stability of the galactose oxidase being decreased at any other values of pH. The enzyme is destabilized at acidic pH that is connected with protonization of its ionogenic group with pK 4.7. The temperature optimum of the galactose oxidase is 35 degrees C. When studying the enzyme thermoinactivation, it was found that at temperatures below 30 degrees C the energy of activation of denaturation was about 40 kcal/mole and at temperatures ranging from 30 to 70 degrees C - 13 kcal/mole. On the basis of the data obtained it was concluded that a low-temperature form of the galactose oxidase, possessing a higher energy of activation of denaturation, is more active than a high-temperature form. The value of Km for the enzyme in respect to galactose was 0.19 M, and the value of Vmax = 360 mumole/min per g of the preparation.