Isolation and characterization of β-glucosidases from Aspergillus nidulans mutant USDB 1183

Two extracellular -glucosidases (cellobiase, EC 3.2.1.21), I and II, from Aspergillus nidulans USDB 1183 were purified to homogeneity with molecular weights of 240,000 and 78,000, respectively. Both hydrolysed laminaribiose, -gentiobiose, cellobiose, p-nitrophenyl--L-glucoside, phenyl--L-glucoside, o-nitrophenyl--L-glucoside, salicin and methyl--L-glucoside but not -linked disaccharides. Both were competitively inhibited by glucose and non-competitively (mixed) inhibited by glucono-1,5-lactone. -Glucosidase I was more susceptible to inhibition by Ag⁺ and less inhibited by Fe²⁺ and Fe³⁺ than -glucosidase II.     

Bewegungsstudien an Anatinen

Zusammenfassung Vorliegende Arbeit ist eine Weiterführung derLorenz'schen Bewegungsstudien an Anatinen aus dem Jahre 1941, fortgesetzt an Mischlingen zwischen den dort beschriebenen Arten. Die sich dabei ergebenden Befunde machten eine erneute Untersuchung der Elternarten notwendig. Außerdem wurden einige Arten beobachtet, deren Verhalten noch nicht untersucht worden war. Fragestellung und Begründung werden in der Einleitung gegeben.Im zweiten Abschnitt werden einige der vonLorenz gemachten Beobachtungen berichtigt. So zeigten einige der Kreuzungen mitbahamensis, daß die vonLorenz bei eben dieser Art als Kurzhoch-werden bezeichnete Bewegungsweise dem Ab-auf anderer Schwimmenten homolog ist. Ebenso ist die eine der beiden vonLorenz als Kurzhoch-werden bezeichneten Verhaltensweisen des Krickerpels als Ab-auf zu deuten. Der Gruß desflavirostre-Erpels wurde auch bei weiblichen Tieren gesehen. BeiAnas acuta wurde ein Kinnheben festgestellt, das sich in der Form stark vom Kinnheben beiplatyrhynchos unterscheidet. Als neue Verhaltensweisen wurden u. a. das Haltungannehmen und das Tendieren beimflavirostre-Erpel beschrieben.Im dritten Abschnitt werden einige Verhaltensweisen und ihre Funktion diskutiert und der Versuch gemacht, eine Motivationsanalyse zu geben.(Zeichnungen vonHermann Kacher)     

Cyclic hexapeptide antagonists of the bradykinin B2 receptor: Receptor binding and solution backbone conformation

Summary Cyclic hexapeptide analogs of bradykinin, based on a folded receptor-bound model of bradykinin, were found to be able to antagonize the action of bradykinin at its B₂ bradykinin receptor. The best of these, cyclo(d-Lys(Arg)-Phe-Ser-d-Tic-Oic- Arg) [compound 17], has affinities at the human and rat B₂ bradykinin receptors of 230 and 8.5 nM, respectively. This potency is significant, since the analogs lack the C-terminal carboxylate group, residues 2–4 and the important interaction of Phe⁵. These constrained analogs may serve as tools for the determination of the receptor-bound conformation of antagonists at the bradykinin receptor and for the design of even smaller and more potent antagonist analogs.Abbreviations Arg(Me) N-methyl-l-arginine - Arg(Me)₂ N,N-dimethyl-l-arginine - Boc t-butoxycarbonyl - Oic (S,S,S)-octahydroindole-2-carboxylic acid - PAM phenylacetamidomethyl - PyBOP benzotriazole-l-yl-oxy-tris-pyrrolidino-phosphonium hexafluorophosphate - Thi -(2-thienyl)-l-alanine - Tic l-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid     

Purification and characterization of flavone-specific β-glucuronidase from callus cultures of Scutellaria baicalensis Georgi

-Glucuronidase from callus cultures of Scutellaria baicalensis Georgi was purified to apparent homogeneity by fractionated ammonium-sulfate precipitation and chromatography on diethylaminoethyl-cellulose, hydroxylapatite and baicalin-conjugated Sepharose 6B. A 650-fold purification was obtained by this purification system. When subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis the purified protein migrated as a single band with a molecular mass of 55 kDa. We determined that the native enzyme has a molecular mass of 230 kDa using gel-filtration chromatography. These results suggested that the enzyme exists as a homotetramer composed of four identical 55-kDa subunits. The enzyme showed a broad pH optimum between 7.0 and 8.0. The K _m values were 9 M, 10 M, 30 M and 40 M for luteolin 3 -O--d-glucuronide, baicalin, wogonin 7-O--d-glucoronide and oroxlin 7-O--d-glucuronide, respectively. The enzyme was most active with flavone 7-O--d-glucuronides.Abbreviations BA N⁶-benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - pI isoelectric point - R _t retention time     

Über den Bau und die Hell-Dunkel-Adaptation der Augen des Polychäten Platynereis dumerilii

Summary The eye of Platynereis dumerilii consists of three components: a short optic nerve, a cup-shaped retina, and a vitreous body within the cup. The opening of the retinal cup is called pupil. The retina is composed of supporting cells and visual cells. The supporting cells are stuffed with dark blue violet pigment granules. The visual cells have orange pigment granules which are only found in the narrow middle piece of the cells. The supporting cell pigment may be lacking in abnormally pigmented eyes. The jellylike matter of the vitreous body apparently is produced by the supporting cells. It is of high protein contents and does not seem to be derived from the cuticle which consists of polysaccharides.The ultrastructure of the photoreceptor region shows club-shaped processes of visual cells. Each club is of low electron density and contains elongate membranous structures. It is surrounded by many microvilli. The clubs correspond to the rods in light microscopy.The eye of Platynereis dumerilii adapts to changes in light intensity by movements of the retina and the rods. The cup-shaped retina spreads towards its pupillar opening thus adapting the pupil area to light intensity. The length of the rods in darkfixed immature specimens is about 20, in light-fixed ones about 7 . In mature specimens (Heteronereis) the length is 46 or 19 respectively.During metamorphosis the eyes enlarge to about three times their original volume. This enlargement is due to an increase in volume of the retina and the vitreous body, not to cell divisions.

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Durchgeführt mit Unterstützung durch ein Stipendium aus Mitteln der Fritz-Thyssen-Stiftung, ferner mit Hilfe der Deutschen Forschungsgemeinschaft.

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Die Anregung zu dieser Arbeit und das Platynereis-Zuchtmaterial verdanke ich Herrn Prof. Dr. C. Hauenschild. Für Hilfe bei der Herstellung des Bildmaterials danke ich Frl. U. Poltz (Freiburg).     

Die Fortpflanzungsbiologie der Solenobien (Lepid. psychidae), Verhalten bei Artkreuzungen und F1-Resultate

Zusammenfassung Da wir in jedem Kapitel oder Unterkapitel bereits Zusammenfassungen gegeben haben (vgl. Inhaltsverzeichnis !), erübrigt es sich, hier nochmals eine Zusammenfassung zu geben. Auch im Kapitel Besprechung der Befunde sind die wichtigsten Schlußfolgerungen hervorgehoben worden.Die Durchführung dieser Arbeit wurde durch ein Stipendium aus dem Schweiz. Nationalfonds ermöglicht. Dem Kuratorium der Stiftung sei wärmstens gedankt. Karl v. Frisch zum 70. Geburtstag.     

Cellular localization of glycoside hydrolases inBacteroides fragilis

The localizations of six glycosidases produced byBacteroides fragilis—-glucosidase, -glucosidase, -galactosidase, -galactosidase, -N-acetylglucosaminidase, and -l-fucosidase—were studied. Cell fractions and cell extracts were obtained by Triton X-100 release, by disruption by freeze-pressing and sonication, and by osmotic release. Isoelectric focusing of a cytoplasmic and of a Triton X-100 extract of the cell wall fraction was performed and revealed differences in the relative distribution of differently charged forms of -N-acetylglucosaminidase. -Galactosidase and alkaline phosphatase were used as cytoplasmic and periplasmic markers, respectively. It is concluded that inB. fragilis -glucosidase is periplasmic, -l-fucosidase and -galactosidase are cytoplasmic, and -n-acetylglucosaminidase is cell associated and bound to the cell envelope by hydrophobic interactions. -Glucosidase and -galactosidase are localized cytoplasmically and/or located in the cell envelope.     

Micropropagation of candelilla,Euphorbia antisyphilitica Zucc

Axillary shoot proliferation was induced in vitro from shoot explants of greenhouse grown candellila (Euphorbia antisyphilitica Zucc). Optimum shoot proliferation was obtained by supplementing a modified Murashige and Skoog [7] medium with 0.13 M naphthalene-acetic acid and 4.44 M 6-benzylaminopurine. Rooting occurred on 100% of shoots transferred to a medium containing half strength salts supplemented with 0.49 M indole-3-butyric acid. Fully rooted plants were transferred to potting soil and established under greenhouse conditions without special acclimatization techniques.     

Basic carboxyl groups of hemoglobin S: Influence of oxy-deoxy conformation on the chemical reactivity of Glu-43(β)

The -carboxyl groups of Glu-43() and Glu-22() of hemoglobin-S (HbS), two intermolecular contact residues of deoxy protein, are activated by carbodiimide atp H 6.0. The selectivity of the modification by the two nucleophiles, glycine ethyl ester (GEE) and glucosamine, is distinct. Influence ofN-hydroxysulfosuccinimide, a reagent that rescues carbodiimide-activated carboxyl (O-acyl isourea) as sulfo-NHS ester, on the overall selectivity and efficiency of the coupling of Glu-22() and Glu-43() with nucleophiles has been investigated. Sulfo-NHS increases the extent of coupling of nucleophiles to HbS. The rescuing efficiency of sulfo-NHS(increase in modification) with GEE and galactosamine as nucleophiles is 2.0 and 2.8, respectively. In the presence of sulfo-NHS, the extent of modification of a carboxyl group is a direct reflection of the extent to which it is activated (i.e., the protonation state of the carboxyl group). The modification reaction exhibits very high selectivity for Glu-43() with GEE and galactosamine (GA) in the presence of sulfo-NHS. From the studies of the kinetics of amidation of oxy-HbS at its Glu-43() (i.e., chemical reactivity) as a function of thepH in the region of 5.5–7.5, the apparentpKa of its -carboxyl group has been calculated to be 6.35. Deoxygenation of HbS, nearly doubles the chemical reactivity of Glu-43() of HbS atpH 7.0. It is suggested that the increased hydrophobicity of the microenvironment of Glu-43(), which occurs on deoxygenation of the protein, is reflected as the increased chemical reactivity of the -carboxyl group and could be one of the crucial preludes to the polymerization process.     

Assimilation of γ-butyrobetaine,and d-and l-carnitine by resting cell suspensions of Acinetobacter calcoaceticus and Pseudomonas putida

The metabolic pattern of utilization of [1,2,3,4-¹⁴C, methyl-³H] -butyrobetaine and d-and l-[1-¹⁴C, methyl-³H]carnitine has been examined with variously grown resting cell suspensions of Acinetobacter calcoaceticus and Pseudomonas putida. Ps. putida grown on d, l-carnitine as the sole source of carbon, degraded only l-carnitine with stoichiometric accumulation of glycinebetaine. Alternatively, when grown on -butyrobetaine, Ps. putida rapidly metabolized -butyrobetaine, and to a lesser but significant extent, both d-and l-carnitine with equivalent formation of trimethylamine and degradation of the betaine carbon skeleton. Ac. calcoaceticus grown on either d,l-carnitine or -butyrobetaine, effectively utilized all three betaines at nearly the same rates. Disappearance of each of these quarternary ammonium compounds was accompanied by stoichiometric formation of trimethylamine and degradation of the carbon backbone. Utilization of the betaines and corresponding formation of trimethylamine by resting cell suspensions of appropriately grown Ac. calcoaceticus and Ps. putida, was essentially abolished under conditions of anaerobiosis and severely impaired in the presence of sodium cyanide, sodium azide, 2,4-dinitrophenol or 2,2-bipyridine. The results of the present investigations with resting cell suspensions of both Ac. calcoaceticus and Ps. putida do not support an earlier suggestion that -butyrobetaine degradation in these organisms proceeds by its prior hydroxylation to l-carnitine. Indeed, disrupted cell-free preparations of Ac. calcoaceticus and Ps. putida grown on either d,l-carnitine or -butyrobetaine showed no detectable -butyrobetaine hydroxylase activity.