Quantitation of phospholipase A2 and phospholipase C activity using alkaline phosphatase impregnated liposomes

Phospholipase A₂ and C activity was quantitated using liposomes impregnated with alkaline phosphatase. Release of alkaline phosphatase was dependent on phospholipase related hydrolysis of intact vesicles. Released alkaline phosphatase was quantitated after addition of its chromogenic substrate p-nitrophenyl phosphate. The lower limit of detectability for phospholipase A₂ and C activity was 0.5 unit/ml. These limits were 10-fold lower than a titrimetric method. Liposome destruction as measured by alkaline phosphatase release was calcium dependent and inhibited by 1 mM EDTA and 1 mM ZnSO₄. The assay was technically simple, generated same day results, and used automated enzyme-linked immunosorbent assay instrumentation.     

Long time tail correlations in discrete chaotic dynamics

A scaling relation is derived connecting the exponent of the algebraically decaying correlation and response functions with the degree of intermittency and the order of the maximum. It is universal, i.e. within a large class independent of the correlated variables. This implies universal 1/f-like spectra. The corrections to scaling are investigated, too.     

First order phase transition in an anharmonic ising lattice

Criteria are derived for the existence of a first order phase transition in a compressible anharmonic Ising lattice. The analysis is based on a variational calculation and on the assumption that a compressible harmonic Ising lattice does not show a first order transition. A first order transition can occure only if the lattice and magnetic Grüneisen constants have the same sign and if the pressure is below some critical value. At this pressure the transition changes from first to second order. The results are applied to ammonium cloride exhibiting an order disorder transition of this type.     

Substitutionsprodukte des Cyclopentadiens, 11. Mitt.: Allylcyclopentadien und (x-Cyclopentadienyl)-allyl-palladium-Komplexe

Zusammenfassung Es wird über Synthese und Reaktionen des Allylcyclopentadiens (I) sowie (Allylcyclopentadienyl)-allyl-palladiums (VIII) und VIII-Analoger berichtet.Fortsetzung der 5. Mitt., Mh. Chem.91, 809 (1960).     

Studien zur Benzotropolonbildung aus 3-Hydroxy-o-benzochinon

Zusammenfassung Die Benzotropolonbildung aus Brenzcatechin- und Pyrogallolderivaten hängt von Art, Größe und Stellung der Substituenten in den Reaktionspartnern ab. Nur in die 5-Stellung des Pyrogallols können elektrophile Substituenten eingebaut werden, ohne daß die Fähigkeit zur Benzotropolonbildung verlorengeht. Dieses Verhalten wird durch die Symmetrie der elektronischen Struktur des als 1,3-Dipol wirkenden Anions erklärt.In 4- und 6-Stellung durch Methyl-, Äthyl- und Phenylgruppen substituierte Pyrogallole liefern mit 3-Methoxy-o-benzochinon Benzotropolone; Isopropyl- undtert. Butylgruppen in den gleichen Positionen verhindern aus sterischen Gründen die Benzotropolonbildung.Es wird versucht, aus der Produktanalyse von Benzotropolongemischen, die durch oxydative Verknüpfung von Brenzcatechinderivaten mit Pyrogallolderivaten hervorgegangen sind, Einblick in die den Mechanismus bestimmenden Faktoren zu erhalten. Verbindliche Aussagen hierüber werden durch die mangelhaften Stoffbildungen unmöglich gemacht.

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The formation of benzotropolone compounds from catechol and pyrogallol derivatives depends upon the type, size, and position of the substituents in the reactants. Electrophilic substituents can be installed only in the 5-position of pyrogallol without loosing the capability of forming benzotropolones. This behavior is explained by the symmetrical electronic structure of the anion acting as 1.3-dipole.Pyrogallols, substituted in the 4- and 6-position by either methyl-, ethyl- or phenyl-groups, yield benzotropolones with 3-methoxy-o-benzoquinone. Isopropyl- andtert. butyl-groups in the same positions hinder benzotropolone formation because of steric hindrance. It was attempted to clarify the effect of the factors on the reaction mechanism by analysis of mixtures of benzotropolones, formed by oxidative coupling of catechol derivatives with pyrogallol-derivatives. On account of deficient yields this could not be done.

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Fritz Wessely in herzlicher Verbundenheit zum 70. Geburtstag gewidmet.

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28. Mitt.:L. Horner undK. H. Weber, Chem. Ber., z. Zt. im Druck.