Synthesen mit Nitrilen, 88. Mitt.: Spiro[indol- und Spiro[inden-pyrano[2,3-c]pyrazole]aus Cyanmethylenderivaten und Pyrazolonen

Summary The reactivity of cyanomethylene-indolones (1 a–e) and 2-(dicyanomethylene)-indan-1,3-dione (4) towards 1,5-disubstituted 3-pyrazolones (2 a–c) was investigated. The reactions yield spiro[indene- and spiro[indole-4- and 6-pyrano[2,3-c]pyrazoles] (3 a–e,5 a–c). The structures are proven by¹³C-NMR-spectroscopy. The mechanisms of the reactions are discussed.

     

Allgemeine Zerlegungstheorie

The notion -disjoint decomposition is introduced as a common generalization of the elementary geometric decomposition of polyhedras and the disjoint decomposition of sets: Let Rø be a set, G a subgroup of the symmetric group S_R and 2^R with ø and ¦¦>1; then A, B 2^R are called -disjoint if ø. is the only set of contained in A B, and then A B A B is called the disjoint union. If fullfills the axioms (0, I, II, III) of §2, then can be provided in a natural way with certain binary relations. With respect to the decomposition equivalence can be turned in a partially ordered commutative semigroup with identity (cf. Satz §5).

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Dedicated to Prof.R.Artzy on the occasion of his 80. birthday     

Crystallization of the E. coli polyamine-induced protein: a novel procedure based on the concept of ionic strength reducers

Nucleation and growth of macromolecular crystals occur in supersaturated solutions the properties of which depend on numerous parameters that influence macromolecular solubility. Detailed knowledge of the effects of those parameters is essential for crystallization. The concept of the so-called “ionic strength reducers” provides insight into the changes of solubility induced by organic solvents and hydrophilic polymers in aqueous electrolytic solutions. A simple and efficient procedure is presented which exploits the properties of ionic strength reducers in the crystallization of proteins. Using this procedure in the crystallization of the E.coli polyamine-induced protein, superior crystals compared to conventional techniques have been obtained. The procedure combines microseeding with dialysis techniques and is applicable to other proteins, particularly in cases where conditions favoring both for nucleation and growth cannot be found, or in cases where excessive nucleation leads to the growth of a large number of very small crystals.     

Efficient ribosomal peptidyl transfer critically relies on the presence of the ribose 2'-OH at A2451 of 23S rRNA

The ribosomal peptidyl transferase center is a ribozyme catalyzing peptide bond synthesis in all organisms. We applied a novel modified nucleoside interference approach to identify functional groups at 9 universally conserved active site residues. Owing to their immediate proximity to the chemical center, the 23S rRNA nucleosides A2451, U2506 and U2585 were of particular interest. Our study ruled out U2506 and U2585 as contributors of vital chemical groups for transpeptidation. In contrast the ribose 2'-OH of A2451 was identified as the prime ribosomal group with potential functional importance. This 2'-OH renders almost full catalytic power to the ribosome even when embedded into an active site of six neighboring 2'-deoxyribose nucleosides. These data highlight the unique functional role of the A2451 2'-OH for peptide bond synthesis among all other functional groups at the ribosomal peptidyl transferase active site.     

The n = 0 replica limit of U(n) and models

Recently the replica limit n = 0 of the U(n) and models have attracted interest since they describe the Anderson localization behaviour in the band-centre of a two-sublattice model. For n ≠ 0 the theories can be decomposed into one with symmetry U(1) and one for SU(n) and . This does not no longer hold for n = 0. We show how the beta-functions and zeta-functions for operators without derivatives can be obtained in this limit from those of SU(n) and and draw consequences for these functions in this limit.     

Zur Synthese von isocamphananalogem Ephedrin

The synthesis of two new bicyclic phenylethylamine derivatives with potentially simpathomimetic effects is described. The synthesis of the isocamphane analogous apoephedrine (4) starts from the bicyclic methylketone5 and leads via its -bromoderivative6 and the corresponding tosylamidoketone8 to4. The synthesis of the title compound2 has been accomplished by preparing the -oximinoketone19 from the bicyclic ethylketone15 with subsequent reduction to the amino alcohol derivative20 and final selective monomethylation by theJohnstone procedure via the corresponding trifluoroacetamide.

Herrn Prof. Dr.K. Kratzl mit den besten Wünschen zum 70. Geburtstag gewidmet.