ISOLATION AND PROPERTIES OF POLYPHENOL OXIDASE FROM BASIDIOCARPS OF Lactarius pergamenus Fr. (Fr.) FUNGI.

Fresh juice of basidiocarps of Lactarius pergamenus Fr. (Fr.) fungi was subjected to ion exchange chromatography with used DEAE-toyopearl and CM-cellulose columns, as well as preparative electrophoresis in 7.5% polyacrylamide gels (pH 8.6). Three isoforms of polyphenol oxidase (PPO) were discovered and two isoforms (1-l and 1-2) were purified with a release of protein 0.42 mg/kg and 0.15 mg/kg of basidiocarps, respectively. These isoforms differ in the mobility at disc-electrophoresis in 7.5% PAGE in alkaline buffer system (pH 8.6). Specfic activity of isoform 1-2 is 4.8 times higher than that of the isoforms 1-1. The molecular weight determination by gel chromatography on the Toyopearl HW-55 demonstrated that both isoforms 1-1 and 1-2 have the same 64 ± 2 kDa molecular mass. Electrophoresis in 15% PAGE in the presence of sodium dodecylsulphate and ß-mercaptoethanol revealed one band with molecular mass of 64 ± 1 kDa which suggests the presence of one polypeptide chain in the molecule ofthe enzyme. The enzyme has demonstrated the highest activity at pH 6.0 and temperature +10 °C, and at +70 °C the enzyme was inactivated. The PPO activity was the highest in young mushrooms and it decreased with their age and positively correlated with the content ofthe milky juice. Ortho-aminophenol was most effective among all the tested substrates to determine the activity of PPO (o-, m- and p-aminophenol, catechol, tyrosine, resorcinol, phloroglucinol) and its relative activity was 129% of the activity of catechol. Ascorbic acid was the most effective inhibitor of the polyphenol oxidase activity which was completely blocked at 1 mM concentration, whereas the same concentration of thiourea and sodium sulphite decreased the enzymatic activity by 40-45%. The PPO in L. pergamenus fungi basidiocarps was mainly localized in the mushroom milky juice where its high activity may be associated with protection of basidiocarps against various pathogens.

Purification of a lectin from fruit bodies of Lactarius pergamenus (Fr.) Fr. and studies of its properties.

A lectin was purified from fruit bodies of the milk mushroom Lactarius pergamenus (Fr.) Fr. by a combination of ethanol precipitation, affinity chromatography on copolymer of polyvinyl alcohol and human blood B-group-specific substance, and ion-exchange chromatography on DEAE-Toyopearl. The lectin yield was 3 mg/kg of fresh mushrooms. Considerable loss of primary activity was observed during its purification, which, presumably, could be explained by disintegration of the lectin molecule, which consisted of six subunits, first to two molecules of three subunits, and then to individual subunits. There was a reverse tendency to aggregation during concentration of lectin solutions. Similar processes can take place in nature because of considerable individual variations of the lectin activity during growth of mushroom fruit bodies. The lectin weakly interacts with DGalNAc, while DGalß1-3DGalNAc and DGalß1-3DGlcNAc are the most probable candidates for ligands, with which the L. pergamenus lectin interacts at disaccharides level. The purified lectin may find application in histochemical research.

Cytotoxic proteins of Amanita virosa Secr. mushroom: purification, characteristics and action towards mammalian cells.

A new hemolytic lectin was purified from the fruit bodies of Amanita virosa Secr. mushroom by the affinity chromatography on the cross-linked ovomucin. This lectin destroyed erythrocytes of human and animals of various species, and its hemolytic activity decreased in the row: rabbit > rat > human > dog. The erythrocytes of sheep, cow and carp were resistant to such hemolytic action of the lectin (1 mg/mL). The lectin-mediated hemolysis was blocked by the polyethylene glycol with molecular mass over 1350. A. virosa lectin, unlike Amanita phalloides lectin, did not interact with tested monosaccharides. However, the 4-nitrophenyl derivates of the monosaccharides inhibited the action of A. virosa lectin which did not prefer targeting O-type glycoproteins over the N-type glycoproteins. Murine leukemia cells of L1210 line and human leukemia T-cells of CEM T4 and Jurkat lines were shown to be sensitive to toxic effect of the lectin and another protein toxovirin isolated from A. virosa fruit bodies It was found that toxovirin possessed an enzymatic activity of L-amino acid oxidase. Since both toxic proteins--the lectin and toxovirin--are sensitive to an elevated temperature, it is suggested that they play a significant role in human poisoning only when the unbaked mushroom is eaten.

Apoptosis-related changes in plasma membrane glycoconjugates of peripheral blood lymphocytes in rheumatoid arthritis.

Control of apoptosis (apo) is very important for diagnosis, prognosis and treatment of rheumatoid arthritis (RA). Recently, we found that an appearance of specific cell surface GC is attributable to apo and developed lectin-induced agglutination test for apo evaluation. The aim of current study was to estimate changes in surface GC expression in peripheral blood lymphocytes (PBL) of normal healthy donors (NHD) and patients with RA, measured by cell agglutination with the galactose-specific VAA lectin and by lectin-cytochemical analysis. In parallel, these changes in apo incidence were evaluated by the detection of cells with sub-G1 DNA content. The data revealed an increased level of apo in lymphocytes of RA patients (n = 29), and increased cell surface GC expression in lymphocytes of NHD (n = 18). A correlation (R = 0.708) was observed between these two indicators. Specific changes in cell surface GC can be effectively used for the detection of apo cells in RA and other autoimmune disorders.

Cytochemical study of role of alpha-d-mannose- and beta-d-galactose-containing glycoproteins in apoptosis.

Recently, we found increased levels of alpha-d-mannose- and beta-d-galactose-containing glycoproteins in plasma membrane of the apoptotic murine leukemia L1210 cells (Bilyy & Stoika 2003). That indicator was suggested to be a novel marker of apoptosis in L1210 cells. The aim of our present work was to reveal if these changes in glycoprotein expression can be common for apoptotic cells of different origin and for various ways of apoptosis induction. It was demonstrated that an elevated expression of plasma membrane glycoproteins rich in alpha-d-mannose and beta-d-galactose did not depend on type of cell line and its tissue origin as well as on nature of apoptosis-inducing agent. We also found that an increase in membrane glycoprotein expression was dependent on concentration of apoptosis-inducing agent and was time-dependent. Changes in glycoproteins' expression were detected as early as 9-12 hours after apoptosis induction. Two hours pretreatment of cells with non-labeled lectin decreased plasma membrane staining with corresponding peroxidase-labeled lectin, probably because of lectin-induced internalization of specific membrane glycoproteins. PSL-lectin-affinity procedure was developed for isolation of apoptotic cells from their mixed population with normal cells. Lectin-dependent agglutination analysis showed that this process occurs at much lower lectin dilutions in the apoptotic cells than in the non-apoptotic cells. Thus, we found that alpha-d-mannose- and beta-d-galactose-containing glycoproteins can be used for lectinocytochemical detection, study and isolation of apoptotic cells.

Purification and partial characterization of L-fucose-specific lectin from fruit bodies of Peziza badia Merat.

An L-fucose-specific lectin from fruit bodies of the ascomycete Peziza badia Merat, was purified by affinity chromatography on agarose-coupled human ovariomucin (serotype H). This lectin binds L-fucose but is not specific to erythrocytes of blood group O(I), similarly to the lectin from Aleuria aurantia ascomycete. Unlike L-fucose-specific plant lectins, the lectin from P. badia binds with human thyroglobulin and mannofucogalactans of aphyllophoric fungi; this suggests that the lectin interacts with L-fucose located inside the polysaccharide chain of the glycoconjugates. Thus, the immunochemical properties of the lectins from P. badia and A. aurantia are similar.