Yeast invertase: Subcellular distribution and possible relationship between the isoenzymes

The intracellular invertase ofSaccharomyces cerevisiae is mainly found in a soluble form (91–95%), while only minor amounts are found bound to the internal (4–8%) and plasma membranes (less than 1%). In the processes of derepression or repression, inhibition of RNA or protein synthesis, or in the presence of 2-deoxy-d-glucose, the levels of the membrane-bound and external activities are modified in a way in which their relation is clear, while the soluble enzyme does not change at all. These results, together with the fact that the membrane-bound and the external enzymes are glycoproteins, suggest a precursor-product relationship between the enzymic forms.     

Glycoproteins in bacterial membranes. In vivo labeling of the sugar portion of energy-transducing ATPase and a low-molecular-weight fraction fromMicrococcus lysodeikticus membranes

The energy-transducing ATPase and a low-molecular-weight fraction ofMicrococcus lysodeikticus membranes incorporated¹⁴C label fromd-[U-¹⁴C]glucose fed to the bacteria in synthetic medium. The specific radioactivity of the sugar portion of the ATPase and low-molecular-weight fraction was, respectively, 2.65 and 2.88 times that of their amino acids. Glucose and mannose in approximately equimolar amounts were identified as the main sugars of the glycoprotein ATPase, thus confirming previous structural studies. Glucose, galactose, and mannose (1:1:2) were identified as the main sugars of the low-molecular-weight glycopeptides. These results confirm and extend the notion that glycoprotein are constituents of prokaryotic membranes.     

Pleurotrema epiphylla Vězda sp. n., eine neue foliikole Flechte aus Zentral-Afrika

Eine nèue foliikole Flechte (Pleurotrema epiphylla sp. n.) aus Zaïre (Zentral-Afrika) wird beschrieben. Die systematischen Beziehungen der neuen Art zu den anderenPleurotrema-Arten und die Stellung der GattungPleurotrema innerhalb der FamilieParatheliaceae wird kurz diskutiert.     

Relationship between the structure of carbonylcyanide phenylhydrazones and inhibition of growth of microorganisms,stimulation of respiration of yeast cells and rat liver mitochondria

The effect of ten derivatives of carbonylcyanide phenylhydrazone on growth of bacteria, yeast and different species of filamentous fungi was investigated. In yeast and mitochondria isolated from rat liver the effect of these derivatives on the respiratory activity was also followed. The relative efficiency of the individual derivatives of earbonylcyanide phenylhydrazone was determined on the basis of the results obtained. It was shown that derivatives, in which the substituent on the benzene ring causes simultaneously an increase of acidity and lipophilicity of the derivative as compared with the non-substituted carbonylcyanide phenylhydrazone (4-trifluoromethoxy-, 3-chloro-, 4-chloro and 3,4-dichloroderivatives) were most effective.     

Separation and properties of α-mannosidase and mannanase from the basidiomycetePhellinus abietis

Proteins of a crude enzyme preparation obtained from the cultivation medium of the basidiomycetePhellinus abietis were separated by gel filtration and ion-exchange chromatography. The preparation contained a minimum of three enzymes capable of splitting α-d-mannosidic bonds: α-mannosidase, exomannanase, and endomannanase, which were separated. Some properties of the mannanase complex of the crude enzyme preparation, and of a partially purified α-mannosidase were examined. The mannanase complex exhibited two pH optima, its temperature optimum being at 46 °C The pH optimum of purified α-mannosidase was at pH 5.0, the temperature optimum was at 60 °C; the enzyme had a relatively high heat stability. The K_m of α-mannosidase forp-nitrophenyl α-d-mannopyranoside was 1.5 x 10⁻⁵ M. Pure α-mannosidase did not split mannan.     

Proteinaceous crystals in cells of virus infected plants

Crystal-containing organelles in cells of virus infected plants lying at chloroplasts and mitochondria are identical with single membrane-bound microbodies containing crystals of catalase described in healthy plants. Massive complex inclusions caused by turnip mosaic virus very frequently contain the same microbodies with crystal inclusions; that phenomenon may be related to some pathophysiological changes of virus infected plants. Comparable proteinaceous crystals, but not lying within microbodies limited by a membrane, may also be found in cytoplasm of infected cells. These crystals are sometimes surrounded by a substance resembling the microbody matrix. Disintegrated cytoplasm of virus infected cells may also contain the same crystals lying free in “empty spaces”. Cytopathological effects responsible for this phenomenon and possible artifacts as well are discussed.