Purification and characterization of chloramphenicol acetyltransferase from Flavobacterium CB60

From the highly chloramphenicol-resistant cytophaga-like bacterium Flavobacterium CB60, which can both acetylate chloramphenicol and degrade it in co-metabolism, the chloramphenicol acetyltransferase (CAT) was purified to homogeneity and characterized. The purification included fractional precipitation with ammonium sulphate and two affinity chromatography steps, eluting CAT the first time with 5 mM-chloramphenicol and the second time with a linear gradient (0-10 mM) of chloramphenicol. The purification was 3979-fold. Properties of this CAT were investigated and compared with CATs from other bacteria. Although CAT from Flavobacterium CB60 shares some properties with the enzymes from Escherichia coli and other Gram-negative bacteria--especially with CATII and CATIII--it has distinct properties like extreme heat lability and the inability to produce diacetylchloramphenicol, so that it might be regarded as a new variant.     

Central projections of the frontal organ of Rana pipiens,as demonstrated by the anterograde transport of horseradish peroxidase

Summary The central projections of the frontal organ of Rana pipiens are more widespread, and more similar to those of the epiphysis, than previously realized. Fibers labeled with horseradish peroxidase were traced to the amygdala, the epiphysis, the pretectal region, and several nuclear areas of the mesencephalic and diencephalic central gray. When peroxidase reaction product was carefully distinguished from neuromelanin by means of polarization microscopy, no unequivocally labeled cell bodies of centrifugal fibers could be found.Supported by NIH grants GM-09181, EY-02083, and by BRSG RR-05357 awarded by the Biomedical Research Grant Program, Division of Research Resources, N.I.H.     

Über das Verhalten des Erbsenwicklers gegenüber Erbsensorten und Erbsen-Neuzuchtstämmen

Zusammenfassung Die Abhängigkeit des Erbsenwicklerbefalls von Blütezeit und Blühdauer wurde in den Jahren 1959 und 1960 an Hand von Gemüse- und Speiseerbsensortimenten in Hadmersleben geprüft. Sorten und Stämme mit frühem Blühtermin und möglichst kurzer Blühdauer wurden nur geringfügig befallen, solche, deren Hauptblütezeit in Perioden großer Falteraktivität fiel, wurden demgegenüber stark befallen. Die Wuchshöhe beeinflußte den Befall nicht. Übereinstimmend konnten für 1959 und 1960 drei Perioden erhöhter Falteraktivität festgestellt werden. Der starke Rückgang der Erbsenwicklerpopulation in der zum VEB Saatzucht Amt Hadmersleben gehörenden Flur wird auf den Erfolg einer Großflächenbehandlung mit Wofatox-Staub und auf einen natürlichen Abfall zurückgeführt.Mit 3 AbbildungenDem Präsidenten der Deutschen Akademie der Landwirtschaftswissenschaften Herrn Prof. Dr. Dr. h. c.Stubbe zum 60. Geburtstag gewidmet.     

Referate

Ohne Zusammenfassung     

Kinetics and thermodynamics of ethanol oxidation catalyzed by genetic variants of the alcohol dehydrogenase from Drosophila melanogaster and D. simulans

Four naturally occurring variants of the alcohol dehydrogenase enzyme (ADH; EC 1.1.1.1) from Drosophila melanogaster and D. simulans, with different primary structures, have been subjected to kinetic studies of ethanol oxidation at five temperatures. Two amino acid replacements in the N-terminal region which distinguish the ADH of D. simulans from the three ADH allozymes of D. melanogaster generate a significantly different activation enthalpy and entropy, and Gibbs free energy change. The one or two amino acid replacements in the C-terminal region between the ADH allozymes of D. melanogaster do not have such clear-cut effects. All four ADH variants show highly negative activation entropies. Sarcosine oxidation by the ADH-71k variant of D. melanogaster has an activation energy barrier similar to that of ethanol oxidation. Three amino acid differences between the ADH of D. simulans and the ADH-F variant of D. melanogaster influence the kappa cat and kappa cat/Kethm constant by a maximum factor of about 2 and 2.5, respectively, over the whole temperature range. Product inhibition patterns suggest a 'rapid equilibrium random' mechanism of ethanol oxidation by the ADH-71k, and the ADH of D. simulans.     

Localization and immunological characterization of the cellulolytic enzyme system in Clostridium thermocellum

Abstract The cellulolytic enzyme complex from Clostridium thermocellum JW 20 was purified from the cellulose to which the enzyme was bound during growth. After centrifugation and gel filtration the enzyme complex was analyzed by SDS-PAGE. Three subunits with apparent molecular weights of 195 000 Da, 97 000 Da and 72 000 Da were purified by preparative SDS-PAGE and electroelution. Polyclonal antibodies directed against these three subunits were raised in rabbits. The specificity of the antisera was tested with immunochemical methods. Cross reactions with other subunits of the cellulase complex were observed. Immunoelectron microscopy of protein-A gold labeled, resin embedded cells indicated that the three types of subunits were located in the outer region of the cytoplasm and on structures at the outside of the cell wall.