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R Toman

Publications and source records attributed to R Toman.

At least 55 records · Page 3Linked to original sources
PubMed1979

On the specificity and mode of action of a xylanase from Trametes hirsuta (Wulf.) Pilát.

The mode of action of the extracellular endo-(1 leads to 4)-beta-D-xylanase produced by Trametes hirsuta on a (4-0-methyl-D-glucurono)-D-xylan and a modified, essentially neutral D-xylan from white willow (Salix alba L.) has been studied. Xylotetraose and xylohexaose, together with aldotetraouronic and aldohexaouronic acids, were the main products. The acidic oligosaccharides had a 4-O-methyl-D-glucopyranosyluronic acid group attached to the non-reducing D-xylosyl end-group. The action pattern of the xylanase corresponds to that of a typical endo-enzyme that acts more readily in the middle of chain, and the specific region of its action appears to involve five D-xylosyl residues. The products of the enzymic treatment of the D-xylan have revealed a regular distribution of the 4-O-methyl-D-glucopyranosyluronic acid groups attached to the D-xylan backbone.

Basidiomycota↗
PubMed1978

Some properties of an endo-1,4-beta-D-xylanase from the ligniperdous fungus Trametes hirsuta.

Some properties of purified endo-1,4-beta-D-xylanase (1,4-beta-D-xylan xylanohydrolase, EC 3.2.1.8) from the ligniperdous fungus Trametes hirsuta were investigated. The enzyme was stable between pH 4.0 and 8.0 were optimum activity at pH 5.0--5.5. The temperature optimum was 50 degrees C and the enzyme was stable for up to 30 min at 45 degrees C; however, it was denatured at higher temperatures. The Km for 4-O-methylglucurono-D-xylan was 6.36.10(-3) equivalents of D-xylose per litre, the activation energy was 28 kJ mol-1. The molecular weight determined by means of gel chromatography was 22000--24000. The enzyme was activated by Ca2+ and inhibited by Ag+ and Hg2+. On the basis of the effect of 2-hydroxy-5-nitrobenzyl bromide. N-bromosuccinimide and N-acetylimidazole it may be assumed that trytophan and possibly tyrosine residues influence the enzyme catalysis.

Amylases↗
PubMed1976

Purification of xylanase from the wood-rotting fungus Trametes hirsuta.

Xylanase (EC 3.2.1.8) was purified from a crude extracellular enzyme of the wood-rotting fungus Trametes hirsuta by a four-step procedure involving precipitation with ammonium sulphate, gel filtration on Bio-Gel P-10, column chromatography on DEAE-Sephadex A-50 and preparative electrophoresis on polyacrylamide gel. The isolated enzyme, electrophoretically homogeneous, was separated from beta-xylo-sylosidase and other hydrolytic enzymes studied. The analysis of the degradation products of water-soluble (4-0-methylglucurono)-D-xylan from willow by the purified xylanase showed it to be endoxylanase (beta-1,4-xylan xylanohydrolase).

Amylases↗
PubMed1969

Gastrointestinal cancer and nutrition.

The hypothesis upon which this study was based is that there is a relationship between mortality from gastrointestinal cancer and living standards. On this basis we found significant correlations between the intake of animal proteins and the mortality rates for gastric and intestinal cancer. The negative correlation coefficient (r = - 0.85) is an expression of the inverse relationship between gastric and intestinal cancer mortality rates. This inverse relationship is also expressed as the correlation between the food intake, expressed by the intake of animal protein, and the respective mortality rates. The higher the food intake, the lower the gastric cancer mortality rate but the higher the intestinal cancer mortality rate. We do not claim that this relationship discovered by correlation analysis is a causal one. On the basis of this study it cannot therefore be said that food intake has a direct effect on the development of gastrointestinal cancer. In this respect our findings can only be a signal for further studies. Secondly no time lag has been proved between food intake and the mortality rate for intestinal cancer. The findings relating to gastric cancer do not contradict the hypothesis of a time lag.

Dietary Proteins↗