Ursula Pieper

Production of a copolyester of 3-hydroxybutyric acid and 3-hydroxyvaleric acid from single unrelated carbon sources by a mutant of Alcaligenes eutrophus

SummaryAlcaligenes eutrophus mutant strain R3, which is a spontaneous revertant to prototrophy of an isoleucine-auxotrophic mutant of the wild-type strain H16, accumulated a copolyester consisting of 3-hydroxybutyric acid (3HB) as main constituent and of 3-hydroxyvaleric acid (3HV), i.e. poly(3HB-co-3HV), as the only other constituent from various single unrelated substrates, which were provided in excess, after a nutrient essential for growth was depleted in the medium. Poly(SHB-co-3HV) was produced from fructose, gluconate, succinate, acetate or lactate during cell starvation of the nitrogen, sulphur or magnesium source. Although 3HV amounted to only 8 mol% of the constituents of the polyester, this study provides a general rationale for construction and utilization of mutants of poly(3HB)-accumulating bacteria that are altered in the metabolism of branched-chain amino acids for the production of poly(3HB-co-3HV) from single unrelated substrates.

Identification, cloning and sequence analysis of the poly(3-hydroxyalkanoic acid) synthase gene of the Gram-positive bacterium Rhodococcus ruber

The first polyhydroxyalkanoic acid (PHA) synthase gene (phbCRr) of a Gram-positive bacterium was cloned from a genomic library of Rhodococcus ruber in the broad-host-range plasmid vector pRK404. The hybrid plasmid harboring phbCRr allowed the expression of polyhydroxybutyric acid (PHB) synthase activity and restored the ability of PHB synthesis in a PHB-negative mutant of Alcaligenes eutrophus. Nucleotide sequence analysis of phbCRr revealed an open reading frame of 1686 bp starting with the rare codon TTG and encoding a protein of relative molecular mass 61,371. The deduced amino acid sequence of phbCRr exhibited homologies to the primary structures of the PHA synthases of A. eutrophus and Pseudomonas oleovorans. Preparation of PHA granules by discontinuous density gradient centrifugation of crude cellular extracts revealed four major bands in an SDS polyacrylamide gel. A Mr 61,000 protein was identified as the PHA synthase of R. ruber by N-terminal amino acid sequence determination.

Monomere Organosamarium(III) Chalkogenolate durch reduktive Spaltung von E–E-Bindungen (E = S, Se, Te)

Abstract The THF adduct of decamethylsamarocene, CP ★ 2 Sm(THF) 2 , reacts with disulfides, diselenides and ditellurides to give organosamarium(III) complexes containing a Smue5f8E bond (E = S, Se, Te). The molecular structures of the complexes CP ★ 2 Sm(S 2 CNMe 2 ) ( 1 ), Cp ★ 2 Sm[TeC 6 H 2 Me 3 -2,4,6](THF) ( 4 ) and Cp ★ 2 Sm[SeC 6 H 2 (CF 3 ) 3 -2,4,6](THF) ( 5 have been determined by X-ray diffraction.

LITHIUM-BIS(DI-TERT-BUTYLFLUORSILYL)PHOSPHID : EIN CYCLISCHES ZWITTERION

Abstract We present the synthesis and X-ray structure of lithiumbis(di-tert-buthylfluorosilyl)phosphide ( 3 ). The molecule possesses a unique dipolar cyclic structure without direct Liue5f8P contact. The Siue5f8P − ue5f8Si bond angle is approximately 100°, similar to that of other lithiumfluorosilylphosphide (I–IV). The energy of 3 , calculated by ab initio methods, explains the invariance of the angle, which allows a comparison with the related amides.

Beiträge zur chemie organometallischer metallacyclischer nebengruppenmetallverbindungen: IX. Eine ungewöhnliche koordinationsgeometrie des platin(II) in dem homoleptischen metallacyclopentankomplex [Li(PMDETA)]2Pt(CH2CH2CH2CH2)2☆

Abstract Reaction of [Li2(Et2O)]P tue5f8(CH 2 CH 2 CH 2 C H2)2 (1) with N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) in diethylether (Et2O) gives [Li(PMDETA)]2P tue5f8(CH 2 CH 2 CH 2 C H2)2 (2). The complex has been characterized by DTA analysis, 1H and 13C NMR spectroscopy and X-ray crystallography. The thermal properties and the structures of 2 and [Li(TMEDA)]2P tue5f8(CH 2 CH 2 CH 2 C H2)2 (3) indicate the significant difference of the influence of PMDETA and N,N,N′,N′-tetramethylethylenediamine (TMEDA) on the platinacyclopentane system.

Synthese von 1,2-Bis(silyl)indolen unter anionischer 1,2-Silatropie

Abstract Under the influence of n-butyllithium, 1-(tert.-butyldimethylsilyl)indole (1) submits to an 1,2-silatropie giving the 2-(tert.-butyldimethylsilyl)indole (2). Treating 2 with n-butyllithium and fluoro- or chlorosilane leads to 1,2-bis(silyl)indoles (3,4). 1 was characterized by crystal structure and 2 by complete 13C-NMR analyses in solution.

Darstellung und Struktur von 2.3-Bis[2,4,6-tris(trifluoromethyl)phenyl]-1,2,3-selenadiphosphiran / Preparation and Structure of 2.3-Bis[2,4,6-tris(trifluoromethyl)phenyl]-1,2,3-selenadiphosphirane

Reaction of the diphosphene RfP=PRf (Rf = 2,4,6-tris(trifluoromethyl)phenyl-) with red selenium affords the selenadiphosphirane 1. The X-ray crystal structure of 1 was investigated.

Zur Reaktion von Dihydroxybiphenylen mit Phosphorpentachlorid - Phosphepine mit Phosphonium- und Phosphoranstruktur

The 2, 2-dihydroxybiphenyl derivatives 1d-f react with phosphorus pentachloride to give the dioxaphosphepinium hexachlorophosphates 3a, 3b, and 17. The trichloro-dioxaphosphepins 8a, 8b, and 21 were discussed as intermediates, which were obtained by chlorination of the 6-chloro-dioxaphosphepins 7a, 7b, and 20. The hydrolysis of the dioxaphosphepins leads to the stable, cyclic phosphates 4a, 4b, 9a, 9b, 11a, 11b, 19a, and 19b. The crystal struc-ture of 4a was determined; two different molecules was observed in the asymmetric unit.

A stable aquo-complex of lithiated di-tert-butylfluorosilanol. Synthesis and crystal structure

Abstract It was possible by crystallizing the lithiated derivative of di-tert-butylfluorosilanol to isolate a stable aquo-complex of this tetrameric compound as the first hydrolysis product. An X-ray diffraction study has revealed the existence of ([R 2 Si(F)OLi] 3 ·[R 2 Si(OH)OLi] ·THF·H 2 O (R = CMe 3 ; THF = tetrahydrofuran). The mechanism of hydrolysis from [R 2 Si(F)OLi] 4 to this aquo-complex is discussed.

Lithium-Iminofluorsilan und Natriumfluorsilylamid – ein Vergleich / Lithium-Iminofluorosilane and Sodium-Fluorosilylamide – a Comparison

The metalation of 2,4,6-tri-tert-butylamino-tert-butylfluoromethylsilane (1) with butyllithium leads to the formation of the LiF adduct of the iminosilane 2. In 2 the silicon atom is pentavalent and four-coordinated. The corresponding sodium compound is the fluorosilylamide 3. The nitrogen has a planar environment in 3.