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Die Synthese der Sequenzen A2—21 (13) und A1—21 (15) der Schafinsulin-A-Kette als monomere cyclische Dicystinpeptidderivate wird beschrieben. Die intrachenaren Cystinbrücken A6—7 und A 11 —20 vermitteln die Löslichkeit dieser Derivate in Dimethylformamid und ermöglichen erstmalig die Reindarstellung vollgeschützter Insulin-A-Kettenderivate. Die während der Synthese eingesetzten Schutzgruppen lassen sich mittels Trifluoressigsäure und 2-Mercaptoäthanol quantitativ entfernen.
Es wird die Synthese der Sequenz A 6–9 des Schafinsulins in der geschützten Form Boc-Cys-Cys-Ala-Gly-OBuᵗ (5) sowie das Verhalten dieses monomeren cyclischen Cystinpeptidderivates gegenüber den in der Peptidchemie gebräuchlichen Reagenzien Bortrifluorid/Eisessig, Triäthylamin und Hydrazinhydrat beschrieben.
Synthese der Sequenz 71—86 des Humanproinsulins, III : Synthese über die Fragmente 71—78 und 79—86
(1979)
As a low-input crop, Miscanthus offers numerous advantages that, in addition to agricultural applications, permits its exploitation for energy, fuel, and material production. Depending on the Miscanthus genotype, season, and harvest time as well as plant component (leaf versus stem), correlations between structure and properties of the corresponding isolated lignins differ. Here, a comparative study is presented between lignins isolated from M. x giganteus, M. sinensis, M. robustus and M. nagara using a catalyst-free organosolv pulping process. The lignins from different plant constituents are also compared regarding their similarities and differences regarding monolignol ratio and important linkages. Results showed that the plant genotype has the weakest influence on monolignol content and interunit linkages. In contrast, structural differences are more significant among lignins of different harvest time and/or season. Analyses were performed using fast and simple methods such as nuclear magnetic resonance (NMR) spectroscopy. Data was assigned to four different linkages (A: β-O-4 linkage, B: phenylcoumaran, C: resinol, D: β-unsaturated ester). In conclusion, A content is particularly high in leaf-derived lignins at just under 70% and significantly lower in stem and mixture lignins at around 60% and almost 65%. The second most common linkage pattern is D in all isolated lignins, the proportion of which is also strongly dependent on the crop portion. Both stem and mixture lignins, have a relatively high share of approximately 20% or more (maximum is M. sinensis Sin2 with over 30%). In the leaf-derived lignins, the proportions are significantly lower on average. Stem samples should be chosen if the highest possible lignin content is desired, specifically from the M. x giganteus genotype, which revealed lignin contents up to 27%. Due to the better frost resistance and higher stem stability, M. nagara offers some advantages compared to M. x giganteus. Miscanthus crops are shown to be very attractive lignocellulose feedstock (LCF) for second generation biorefineries and lignin generation in Europe.
Most drugs are no longer produced in their own countries by the pharmaceutical companies, but by contract manufacturers or at manufacturing sites in countries that can produce more cheaply. This not only makes it difficult to trace them back but also leaves room for criminal organizations to fake them unnoticed. For these reasons, it is becoming increasingly difficult to determine the exact origin of drugs. The goal of this work was to investigate how exactly this is possible by using different spectroscopic methods like nuclear magnetic resonance and near- and mid-infrared spectroscopy in combination with multivariate data analysis. As an example, 56 out of 64 different paracetamol preparations, collected from 19 countries around the world, were chosen to investigate whether it is possible to determine the pharmaceutical company, manufacturing site, or country of origin. By means of suitable pre-processing of the spectra and the different information contained in each method, principal component analysis was able to evaluate manufacturing relationships between individual companies and to differentiate between production sites or formulations. Linear discriminant analysis showed different results depending on the spectral method and purpose. For all spectroscopic methods, it was found that the classification of the preparations to their manufacturer achieves better results than the classification to their pharmaceutical company. The best results were obtained with nuclear magnetic resonance and near-infrared data, with 94.6%/99.6% and 98.7/100% of the spectra of the preparations correctly assigned to their pharmaceutical company or manufacturer.
Marine Planktonalgen der Arktis I. Die Haptophycee Phaeocystis pouchetii / Baumann, M. ; Jahnke, J.
(1986)