Jozef Rosík
Institute of Chemistry, Slovak Academy of Sciences
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Featured researches published by Jozef Rosík.
Carbohydrate Research | 1968
Vladimír Kováčik; Š. Bauer; Jozef Rosík; P. Kováč
Electron impact mass spectra of a series of aldobiouronic and pseudoaldobiouronic acid per-0-methyl derivatives and of the corresponding 4,5-unsaturated analogues, found normally among the products of methylation of uronic acid containing disaccharides as a result of methylation accompanying &elimination, have been studied. Using labelling experiments, metastable transition measurements and high resolution mass spectrometry, the fragmentation mechanisms of substances of this class have been deduced. Application of the information to the structure elucidation of this type of compound is discussed. It is concluded that from the mass spectra alone it is possible to determine the molecular weight, the cycle masses as well as the mode of linkage between the monomeric units. The appearance potentials of ions formed by cleavage of the glycosidic linkages have also been determined and the energetic differences encountered in the fission of the glycosidic linkages of various types of uronic acid containing oligosaccharides are discussed.
Carbohydrate Research | 1983
Peter Capek; Rudolf Toman; Alžbeta Kardošová; Jozef Rosík
Abstract A water-soluble l -arabinan isolated from the mucous material of the roots of the marsh mallow ( Althaea officinalis L.) has a highly branched structure of ∼90 α- l -arabinofuranosyl residues variously linked by (1→5), (1→3), and (1→2) bonds. Some of the l -arabinosyl groups are involved in branches through O-2, O-3, and O-5. There was good agreement between the results obtained by chemical and 13 C-n.m.r.-spectroscopic methods. The polymer has essentially the same structural features as those found for l -arabinans isolated from other plant sources.
Carbohydrate Research | 1968
Vladimír Kováčik; Š. Bauer; Jozef Rosík
Abstract The mass spectra of methyl ester methyl glycosides of methylated uronic acids, methyl ester methyl glycosides of methylated aldobiouronic acids of different types, and of methyl ester methyl glycosides of acetylated aldobiouronic acids having 4- O -methyl- d -glucuronic acid as the acidic component were obtained. Fragmentation patterns of these compounds, characteristic features of their mass spectra, and their importance for analytical applications are discussed.
Folia Microbiologica | 1978
Alžbeta Kardošová; Jozef Rosík; Jozef Kubala
Extra- and intracellular glycanohydrolases were isolated fromAspergillus flavus and partially characterized. Both preparations exhibited β-galactosidase activity. Gel chromatography of the extracellular enzyme preparation on Sephadex revealed one protein fraction containing β-galactosidase activity and a second one exhibiting mainly β-xylosidase activity. Electrophoresis in starch gel and disc electrophoresis in polyacrylamide gel showed that the preparation obtained from the cultivation broth contained five protein fractions, whereas two protein fractions could be detected in the intracellular preparation. Hydrolysis of a partially degraded polysaccharide of peach gum by the above preparations yieldedd-galactose as the main product and traces ofd-mannose,l-arabinose,d-xylose and a number of oligosaccharides.
Phytochemistry | 1975
Alžbeta Kardošová; Jozef Rosík; Jozef Kubala
Abstract d -Galactose, d -mannose, d -xylose, l -arabinose, and d -glucuronic acid and its γ-lactone were examined as carbon sources for the culture of Aspergillus flavus . d -Mannose was taken up the most rapidly and d -glucuronic acid and its γ-lactone the least rapidly. A partially degraded polysaccharide from peach tree gum ( Prunus persica [ L. ] Batsch containing the above sugars together with d -glucuronic acid and its 4- O -methyl ether was used as substrate for another A. flavus culture. It was found that d -galactose was the major sugar passing into the culture medium with lower proportions of d -xylose, l -arabinose, 2- O -β- d -glucopyranuronosyl- d -mannose, and 6- O -β- d -glucopyranuronosyl- d -galactose. This indicates that the fungus produces extracellular exo- and endo-glycanohydrolases which may be useful in structural studies on polysaccharides.
Carbohydrate Research | 1971
Jozef Rosík; Alžbeta Kardošová; Jozef Kubala
Carbohydrate Research | 1982
Rudolf Toman; Jozef Rosík; Miroslav Zikmund
Collection of Czechoslovak Chemical Communications | 1984
Peter Capek; Rudolf Toman; Jozef Rosík; Alžbeta Kardošová; František Janeček
Carbohydrate Research | 1988
Peter Capek; Dušan Uhrín; Jozef Rosík; Alžbeta Kardošová; Rudolf Toman; Vincent Mihálov
Collection of Czechoslovak Chemical Communications | 1966
Jozef Rosík; V. Zitko; Š. Bauer; J. Kubala