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By modifying carbohydrate component of glycoproteins it is possible to elucidate its role in manifestation of structural and functional properties of the enzyme. The comparison of activity and stability of the native and modified by oxidation with sodium periodate α-galactosidase of Cladosporium cladosporioides was carried out. To determine α-galactosidase activity the authors used n-nitrophenyl synthetic substrate, as well as melibiose; raffinose and stachyose. Modification of the carbohydrate component had a significant effect on catalytic properties of the enzyme. Both the reduction of V and enzyme affinity for natural and synthetic substrates were observed The native enzyme retained more than 50% ofthe maximum activity in the range of 20-60 °C, while for the modified enzyme under the same conditions that temperature range was 30-50 °C. The modified α-galactosidase demonstrated a higher thermal stability under neutral pH conditions. The residual activity of the modified α-galactosidase was about 30% when treated with 70% (v/v) methanol, ethanol and propanol. About 50% of initial activity was observed when 40% ethanol and propanol, and 50% methanol were used. It was shown that the modification of C. cladosporioides α-galactosidase by sodium periodate is accompanied by a significant decrease in enzyme activity and stability, probably caused by topological changes in the tertiary and quaternary structure of the protein molecule.

The effect of the glycosylation inhibitors (tunicamycin and 2-deoxy-D-glucose) on the activity, stability and production of fungal glycosidases has been studied. It was shown that inhibition of N-glycosylation sites did not affect the secretion of Aspergillus niger α-galactosidase, however reduced yield of Cladosporium cladosporioides and Penicillium canescens α-galactosidases. Changes in the level of O-glycosylation resulted in a significant reduction in the activity and stability of α-galactosidases of all three producers tested. Activity of the modified enzymes was significantly lower than that of the native ones, and was 2.6 and 0.33 U/mg for A. niger α-galactosidase, 3.3 and 32.5 U/mg for C. cladosporioides α-galactosidase, 11.66 and 31.1 U/mg for P. canescens α-galactosidase, respectively. A. niger α-galactosidase completely lost activity during purification and storage. The decrease of thermal stability at 55 °C by 20% was shown for C. cladosporioides and P. canescens α-galactosidases. It was also noted that O-deglycosylation led to a decrease in resistance of these enzymes to the action of proteases.

The influence of a number of coordinative compounds of zinc with N-substituted thiocarbamoil-N'-pentamethylensulfenamides on activity of elastase, alpha-L-rhamnosidase and alpha-galactosidases evidence for a possibility of their usage as stimulators or inhibitors of enzymes tested have been studied. It was shown that all the compounds in concentration of 0.1 and 0.01% inhibited by 90-100% Bacillus thuringiensis 27-88Els+ elastase activity. [Zn(L2)Br2], [Zn(L1)(NCS)2] and [Zn(L3)(NCS)2] at 20 h exposition activated Cryptococcus albidus 1001 alpha-L-rhamnosidase activity. The rest of compounds influenced it on the control level or inhibited it by 7-23%. The obtained results testify that essential role is not played by separate fragments (L-ligand and anions), but by molecules of zinc complexes as a whole. All the studied complexes, exept for [Zn(L3)(NCS)2], induced alpha-L-rhamnosidase activity of Eupenicillium erubescens 248 (7 to 60%). All zinc compounds (concentration 0.01%, exposition time - 60 min) influenced at the control level Aspergillus niger and Cladosporium cladosporioides alpha-galactosidases activity, however inhibited (up to 20%) activity of Penicillium canescens alpha-galactosidase. The increasing of exposition time of the compounds tested with enzymes up to 20 h testify to selective action of separate compounds on enzymes tested. The data obtained prove, that the character of interaction of zinc complexes is changed depending on the enzyme tested and its strain-producer.

The kinetics and mechanism of thermal inactivation of Penicillium canescens alpha-galactosidase in the temperature range of 55-65 degrees C have been studied. The kinetic scheme of alpha-galactosidase thermal inactivation was proposed which included the reversible dissociation of active hexamers into associating monomers and irreversible denaturation of monomers. The kinetic constants of thermal inactivation have been determined. The effect of enzyme concentration and purification efficiency has been investigated. A possibility of defence of protein molecule from thermal inactivation in the presence of BSA, glycerol, melibiose, raffinose and stachyose is shown.

Activity of alpha-N-acetylgalactosaminidase and alpha-galactosidase isolated from the culture medium of micromycete Aspergillus niger v. Tiegh F-16694 has been studied as affected by anions, cations and specific chemical reagents (n-chlormercurybenzoate, L-cysteine, dithiotreitol, beta-mercaptoethanol, EDTA, o-phenanthroline, sodium azide, hydrogen peroxide). It has been established that silver ions noncompetitively inhibit alpha-galactosidase at pH 5.2, the inhibition constant (Ki) being 2.5 x 10(-4) M. Galactose in concentration of 1-5 mM does not protect the enzyme from the negative action of silver ions, but this inhibitory effect is almost completely removed by the corresponding concentrations of L-cysteine. The same noncompetitive character was inherent in the inhibition of alpha-galactosidase reaction by mercury ions and n-chlormercurybenzoat (Ki is 4.5 x 10(-6) and 1.8 x 10(-4), respectively). The importance of sulphydryl groups for the support of active comformation of alpha-galactosidase molecule was established on the basis of inhibition and kinetic analysis. It has been shown that the enzyme molecule does not contain the groups which include metal atoms.

Germanium complexes (IV) with succinic (H2Suc), oxyethyliminodiacetic (H2Oeida) and iminodisuccinic (H4Ids) acids as well as homo- and heteroligand germanium complexes (IV)--products of interaction of triammonium salt of oxyethylidendiphosphonic acid ((NH4)3HL) and oxyacids: tartaric (H4Tart), citric (H4Citr), trioxyglutaric (H4Toglut) acids have been synthesized. Composition of the obtained complexes: [Ge(OH)2(NaSuc)2].2H2O (I); [Ge(OH) (Oeida).H2O].H2O (II); [Ge(OH)2(NaHIds)2] (III); [Ge(OH)2(NH4)3HL) (H2Tart)] (IV); [Ge(OH)2(NH4)3HL) (H2Citr)] (V); [Ge(OH)2(NH4)3HL) (H2Toglut)] (VI); [Ge(OH)2((NH4)2HL)2] (VII); [Ge (OH)2((NH4)2HL)2] (VII); [Ge(OH)2 (H2O)2(NH4) HL] (VIII) has been determined. The capability of the synthesized compounds has been studied to affect synthesis and activity of the following enzymes: collagenase, alpha-N-acetylgalactosaminidase (alpha-GalNAc-ase) and alpha-galactosidase (alpha-Gal-ase). It has been established that the complexes II-VIII activate biosynthesis of alpha-Gal-ase and alpha-GalNAc-ase, while germanium dioxide (IX) and complex I possess considerable inhibiting effect on synthesis of the above enzymes. It has been also established that all the compounds except for IV increased the activity of both alpha-Gal-ase and alpha-GalNAc-ase. All the considered complexes demonstrated similar reaction with respect to collagenase: they inhibited both synthesis and activity.

Different factors have been investigated for their effect on the process of biosynthesis of alpha-N-acetylgalactosaminidase and alpha-galactosidase of Aspergillus niger under deep-water cultivation. Optimal sources and concentrations of carbon (soy flour--25 g/l) and nitrogen (pepton--7.5 g/l) were estimated. It has been established that temperature of 25 degrees C, pH 6.0, growing in 50 ml medium at the swing velocity 220 rev/min. for 6-8 days are optimal cultivation parameters. It has been shown that dry borine blood (in concentration of 1%) and a number of guanidine derivatives (guanidine carbonate--0.25%, nitroaminoguanison dimethylaminobenzaldehyde--0.05%, nitroaminoguanison of salicylic aldehyde--0.1%) can play the part of inducers of the mentioned glycosidase synthesis. When growing fungal culture in selected conditions synthesis of enzymes increased almost 3 times. Activity of alpha-N-acetylgalactosaminidase was 0.46 E/ml, and alpha-galactosidase--1.9 E/ml.