Large Scale Bioprocess for the Production of Optically Pure L-Carnitine

A competitive production method using the biotransformation of 4-butyrobetaine to enantiomerically pure L-carnitine was developed and scaled-up by Lonza. The process produces L-carnitine in 99.5% yield, and >99.9% enantiomeric excess (ee). Continuous and discontinuous processes were developed but the fed-batch process was found to be economically the most favourable process mode.     

Correction for Inner Filter Effects in Fluorescence Spectroscopy

A method is proposed for correcting experimental fluorescence readings for inner filter effects, i.e. the absorption of the exciting light and/or the absorption of the emitted radiation, which cause the non-linearity between fluorescence intensity and fluorophor concentration. Basically the method consists of measuring the fluorescence intensity at two different points along the diagonal in the cell. Unlike similar methods proposed in the literature, the two points are corrected simultaneously for both absorption of excitation and of emission radiation without the necessity of reading the optical density of the solution, and with a very simple data elaboration.     

Novel cellulose fibre reinforced thermoplastic materials

Spun cellulose fibres from the viscose, lyocell and carbamate processes have been used to reinforce thermoplastic commodity polymers, such as polypropylene (PP), polyethylene (PE) and (high impact) polystyrene (HIPS) as well as poly(lactic acid) (PLA) and a thermoplastic elastomer (TPE) for injection moulding applications. A specially developed double pultrusion technique has been employed for compounding. Fibres were analysed in single fibre tensile tests. Strength, stiffness, impact strength, and heat distortion temperature (HDT) were determined for injection-moulded standard test specimen and structural features were revealed by scanning electron microscopy. A strong reinforcing effect was observed in all cases. In particular, high tenacity tyre cord rayon gives excellent composite strength and impact strength, often doubling or tripling the pristine matrix values. In the case of PP, Lyocell type fibres provide enhanced stiffness and HDT, and thus the combination of both fibre types leads to a balanced composite property profile. The PE case is very similar to PP. For HIPS mainly strength and stiffness is increased, while for TPE the property profile is changed completely. With PLA, a biogenic and biodegradable composite with excellent mechanical properties is presented.     

“Push-Pull”-Acetylene für die Peptid-Synthese

“Push-Pull” Acetylenes as Reagents for Peptide Synthesis A series of ‘push-pull’ acetylenes 1 is easily available from the corresponding “push-pull” olefins by a simple bromination-dehydrobromination sequence. The versatility of the acetylenes with regard to peptide synthesis is discussed.     

Solid-phase synthesis of oxazolidinones by cycloaddition of resin-bound epoxides with isocyanates

The first solid-phase synthesis of oxazolidinones by cycloaddition of resin-bound epoxides with isocyanates is described. Synthesis of the title compounds was achieved by alkylation of resin-bound carbamates with glycidyl tosylate, followed by cycloaddition of the resulting epoxides with isocyanates at elevated temperature in high yields and purity. Because N-aryloxazolidinones have been known to possess various biological activities, this method is useful from the viewpoint of drug discovery.     

Chemie der α-Aminonitrile 1. Mitteilung Einleitung und Wege zu Uroporphyrinogen-octanitrilen

Chemistry of α-Aminonitriles I: Introduction and Pathways to Uroporphyrinogen-octanitriles. An introduction to experimental studies on the chemistry of α-aminonitriles potentially relevant to the problems of prebiotic chemistry is presented. The framework of conditions wherein the investigation is chosen to be carried out implies both molecular oxygen and - whenever feasible - water to be excluded from reaction conditions. This study focusses on 2-amino-2-propenenitrile ( 3 ) (Scheme 6) as central starting material of reaction sequences which aim at the nitrile forms of proteinogenic amino acids as well as at the aza forms of building blocks of biological cofactor molecules as their targets (Scheme 5). Schemes 13,16,23 as well as 25 and 26 summarize reaction sequences by which 3 is transformed within the defined framework of conditions into the thermodynamic (statistically controlled) mixture of the four isomeric uroperphyrinogen-octanitriles 57–60 . HPLC's of such mixtures document the dominance of the least symmetrical isomer whose constitutional pattern of peripheral substituents happens to be the one percent in all biological porphinoids. Preparative procedures for the synthesis of 3 (Scheme 9), the β,β-disubstituted pyrrol-nitriles 30,53 and 54 (Scheme 19) as well as the porphyrinogenoctakis(propionitrile) and-octakis(acetonitrile) 65 and 66 , respectively (Scheme 24) are given.     

Reaktionen von Alkoholen und Mercaptanen mit Tetraphosphatrichalkogenadiiodiden

Reactions of Alcohols and Mercaptans with Tetraphosphorus Trichalcogenide Diiodides α-P₄E₃(I)R and α-P₄E₃R₂ (R = -OCH₃, -OC₂H₅, -OCH(CH₃)₂, -OC(CH₃)₃ and -OC₆H₅) have been detected in the reaction solutions of α-P₄E₃I₂ (E = S, Se) with alcohols in the presence of triethylamine, or with trimethyltin alkoxides in CS₂. β-P₄S₃I₂ reacted with methanol at 243 K in CS₂ to yield β-P₄S₃(I)OCH₃, β-P₄S₃(OCH₃)_exo(OCH₃)_endo, and β-P₄S₃[(OCH₃)_exo]₂. The thiolates α-P₄Se₃R₂′ (R′ = -SC₂H₅, -n-SC₅H₁₁, -n-SC₇H₁₅, -SC(CH₃)₃ and -SC₆H₅) were found in reaction solutions of α-P₄Se₃I₂ with thiols HR′. The ³¹P NMR data of these compounds are given.     

Synthese von Benzofulvenen und Dibenzofulvenen über 1-Chloralkyl-acetate

Synthesis of benzofulvenes and dibenzofulvenes via 1-chloroalkyl-acetates 1,2-Benzofulvene (6a) and 1,2,3,4-dibenzofulvene (7a) as well as the corresponding 6-methyl- and 6-phenyl-derivatives are prepared by reaction of sodium indenide and sodium fluorenide with 1-chloroalkyl acetates (3) , followed by elimination with KOC(CH₃)₃. The over-all yields are comparable with the results of the fulvene series and are in most cases considerably higher than the yields of the Thiele-method.     

Biochemical dissection of the mitochondrial proteome from Arabidopsis thaliana by three-dimensional gel electrophoresis

We report a subdivision of the mitochondrial proteome into defined sets of proteins, which is based on the combination of three different gel electrophoresis procedures. First, Blue-native polyacrylamide gel electrophoresis is employed to separate mitochondrial protein complexes. The protein complexes are electroeluted and completely detached from Coomasssie blue. Subsequently the subunits of the protein complexes are separated by isoelectric focusing and finally by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The resolution capacity of the procedure is demonstrated for the ATP synthase complex, the cytochrome c reductase complex and the preprotein translocase of the outer mitochondrial membrane (the TOM complex). The method allows the separation of isoforms of subunits forming part of protein complexes, whose occurrence seems to be rather a rule than an exception in higher eukaryotes. Furthermore, extremely hydrophobic proteins are detectable on the gels.