Comprehensive Analysis of Carbohydrate-Active Enzymes from the Filamentous Fungus Scytalidium candidum 3C.

Complete enzymatic degradation of plant polysaccharides is a result of combined action of various carbohydrate-active enzymes (CAZymes). In this paper, we demonstrate the potential of the filamentous fungus Scytalidium candidum 3C for processing of plant biomass. Structural annotation of the improved assembly of S. candidum 3C genome and functional annotation of CAZymes revealed putative gene sequences encoding such proteins. A total of 190 CAZyme-encoding genes were identified, including 104 glycoside hydrolases, 52 glycosyltransferases, 28 oxidative enzymes, and 6 carbohydrate esterases. In addition, 14 carbohydrate-binding modules were found. Glycoside hydrolases secreted during the growth of S. candidum 3C in three media were analyzed with a variety of substrates. Mass spectrometry analysis of the fungal culture liquid revealed the presence of peptides identical to 36 glycoside hydrolases, three proteins without known enzymatic function belonging to the same group of families, and 11 oxidative enzymes. The activity of endo-hemicellulases was determined using specially synthesized substrates in which the glycosidic bond between monosaccharide residues was replaced by a thio-linkage. During analysis of the CAZyme profile of S. candidum 3C, four ß-xylanases from the GH10 family and two ß-glucanases from the GH7 and GH55 families were detected, partially purified, and identified.

[EFFECT OF FUCOIDANS ISOLATED FROM SEAWEEDS LAMINARIA DIGITATA AND FUCUS VESICULOSUS ON CELL LINES HELA G-63, ECV 304 AND PC 12].

The aim of the research was to investigate cytotoxicity of fucoidans on mammals cells. Three different samples of fucoidans were isolated from mechanically grounded brown algae Laminaria digitata and Fucus ve- siculosus. The sample F2 that differed from the others by higher sulfatation level and suppression of HeLa G-63 line culture growth was taken for further study in cell lines HeLa G-63, ECV 304 and PC 12. We have shown that fucoidan preparation F2 inhibits proliferation and induces cell death in a dose- and time-dependent manner for all investigated cell lines. Neuroendocrine tumor rat cell line PC 12 appeared to be the most sensitive to fucoidan treatment whereas endothelial human cells ECV 304 were the least sensitive.

Improvement of the efficiency of transglycosylation catalyzed by α-galactosidase from Thermotoga maritima by protein engineering.

At high concentrations of p-nitrophenyl-α-D-galactopyranoside (pNPGal) as a substrate, its hydrolysis catalyzed by α-galactosidase from Thermotoga maritima (TmGalA) is accompanied by transglycosylation resulting in production of a mixture of (α1,2)-, (α1,3)-, and (α1,6)-p-nitrophenyl (pNP)-digalactosides. Molecular modeling of the reaction stage preceding the formation of the pNP-digalactosides within the active site of the enzyme revealed amino acid residues which modification was expected to increase the efficiency of transglycosylation. Upon the site-directed mutagenesis to the predicted substitutions of the amino acid residues, genes encoding the wild type TmGalA and its mutants were expressed in E. coli, and the corresponding enzymes were isolated and tested for the presence of the transglycosylating activity in synthesis of different pNP-digalactosides. Three mutants, F328A, P402D, and G385L, were shown to markedly increase the total transglycosylation as compared to the wild type enzyme. Moreover, the F328A mutant displayed an ability to produce a regio-isomer with the (α1,2)-bond at yield 16-times higher than the wild type TmGalA.