Polyhydroxyphenyläther aus Laminaria ochroleuca

After acetylation of the phenolic fraction, the following compounds were isolated from Laminaria ochroleuca: phloroglucinol triacetate, diphlorethol pentaacetate (2,4,6,3′,5′-pentaacetoxydiphenyl ether) and triphlorethol C heptaacetate (1-acetoxy-3,5-bis(2,4,6-triacetoxyphenoxy)benzene).     

Neues aus der Paläoneurologie

Progress in paleontological brain research is demonstrated by giving some examples of recent discoveries which illustrate the various possibilities of studies in this field. An enlarged English text, with details and figures of the specimens cited, will be published in the Proceedings of the 3rd International Conference of Neurobiologists.     

Mykologische Beiträge aus der West-Slowakei

Ohne Zusammenfassung     

Zwei tertiärePotamogeton-Arten aus der SectionHeterophylli Koch

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Eine neue Rubiaceen-Gattung aus der ägyptischen Flora

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Phänologische Mittheilungen aus der Winterflora Ragusa's

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Durch äther erzeugte,atypische Entwicklung des Gehirns der Salamanderlarve

Ohne ZusammenfassungFortsetzung der in diesem Archiv, Bd. XXIV, 1907, erschienenen Arbeit: Die quantitative und qualitative Wirkung der ätherlymphe auf das Wachstum des Gehirns der Salamanderlarve. Ausgegeben am 13. August 1907.     

Kompartimentierung und Eigenschaften der MDH-Isoenzyme aus Wassermelonenkeimblättern

Summary Five MDH-isoenzymes (I–V) from cotyledons of dark-grown water-melon seedlings older than 2 days can be identified by disc-electrophoresis. By isolating and fractionating cell organelles (10000 g fraction) by density gradient centrifugation (Fig. 1) the following compartmentation of the MDH-isoenzymes can be shown: the mitochondria contain isoenzyme III and the glyoxysomes preponderantly (if not exclusive) isoenzyme V (Fig. 2), whereas the isoenzymes I, II, and IV belong to the cytosol.The 5 MDH-isoenzymes differ in several properties, e.g. differential precipitation by ammonium sulfate (Fig. 4) or isoelectric point (Fig. 5). The glyoxysomal MDH is a relatively basic protein (isoelectric point at pH 8.7), whereas the isoelectric points of the other isoenzymes lie between pH 6.4 (IV) and pH 4.7 (I).     

Laubblätter aus dem Älteren Tertiär der Lausitz

Ohne ZusammenfassungMit 29 Textabbildungen (88 Einzelbildern).     

Allosterische Regulation der Aktivität der Glutamatdehydrogenase aus Erbsenkeimlingen durch das Substrat α-Ketoglutarsäure

Summary Several investigations on the properties of glutamate dehydrogenase from plant sources indicate that the enzymatic activity (reductive amination) follows a Michaelis-Menten-type kinetic when velocity is plotted versus rising concentrations of the substrate -ketoglutarate. In the course of our investigations on the effect of SO₂ on pea plant enzymes we found that SO ₄ ^2- , added as (NH₄)₂SO₄ to the assay system, causes this type of activity response because of its ability to function as an activator. When (NH₄)₂SO₄ is replaced by NH₄Cl in the in vitro system however, activity response is sigmoidal. Addition of competitive inhibitor to the latter system again gives rise to a sigmoidal kinetic with reduced initial velocities. Identical kinetic behaviour is observed when either 120 fold enriched enzyme from shoots or highly purified glutamate dehydrogenase from pea roots is used, a fact which justifies the assumption that the enzyme from pea plants belongs to the MIC-type of regulatory proteins (modulator independent cooperativity). The activity response caused by other effectors, especially purine nucleotides, is discussed with regard to the above findings.     

Indolacetamid—ein Intermediat der Indolessigsäurebildung aus Indolacetonitril bei der Alge Furcellaria

Summary The red algae Furcellaria fastigiata, Nemalion multifidum, and the green alga Cladophora rupestris were able to hydrolyse IAN to IAA. The conversion of IAN to IAA by Furcellaria and probably by Cladophora included indoleacetamide as an intermediate.When the brown algae Fucus vesiculosus, Pylaiella litoralis, and Halidrys siliquosa were incubated with IAN, the only products formed were indolecarboxaldehyde and indolecarboxylic acid.