Lipase-katalysierte Racematspaltungen von Cyanhydrinen und deren Umsetzung zu enantiomerenreinen 2-Aminoalkoholen und Derivaten

SIGLEAvailable from TIB Hannover: DW 7042 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Glutathione reductase: purification from brain, localization of the enzyme in neural cells and search for tissue specific isoforms

Über die Glutathionreduktase (GR) des Gehirns ist nur wenig bekannt, ihre Funktion ist aber essentiell zur Erhaltung des hohen Verhältnisses [GSH]/[GSSG] in Gehirnzellen. Deshalb sollte GR aus Hirn gereinigt, enzymatisch charakterisiert, in verschiedenen Hirnzelltypen untersucht und nach Isoformen dieses Enzyms gesucht werden. GR wurde aus Rinderhirn zur Homogenität gereinigt. Das dimere Enzym besaß eine spezifische Aktivität von 145 U/mg Protein und eine Molekülmasse der Untereinheiten von 54 kDa. Neben der GR wurde das cytosolische Malatenzym zur Homogenität gereinigt, das eine spezifischen Aktivität von 40 U/mg hatte. Die Molekülmasse der Untereinheiten beträgt 64 kDa. Mit dem Reinigungsschema, das für die GR aus Rinderhirn entwickelt wurde, ließen sich auch die GR aus Rinderleber und -modifiziert- die GR aus Rindererythrocyten reinigen. Die spezifische Aktivität für die gereinigte GR aus Leber betrug 147 U/mg, für die GR aus den Erythrocyten 114 U/mg. Die Präsenz der GR in astroglia-reichen und neuronen-reichen Primärkulturen wurde durch Nachweis der spezifischen Aktivität gezeigt. Gegen die aus Rinderhirn gereinigte GR wurde ein Antiserum gewonnen, das geeignet war, das Enzym spezifisch durch Immunoblot-Experimente und immuncytochemische Anfärbungen in neuralen Zellen nachzuweisen. Immuncytochemische Doppelanfärbungen neuraler Kulturen gegen GR und zelltypspezifische Marker identifizierten Microglia-, Oligodendrogliazellen und Neuronen als deutlich GR enthaltende Zelltypen. Astrogliazellen wiesen nur schwache Immunreaktivität für GR auf. Mit mehreren proteinanalytischen und immunologischen Methoden wurde versucht, Unterschiede zwischen den gereinigten GR aus Rinderhirn,- leber und -erythrocyten festzustellen. Dabei erwiesen sich die drei Enzyme als äußerst ähnlich. Nur die massenspektrometrische Analyse tryptischer Peptide der GR aus Gehirn und Leber läßt auf Unterschiede dieser Enzyme und somit auf Isofomen schließen.Little is known about glutathione reductase (GR) from brain, although its function is essential for the maintenance of the high [GSH]/[GSSG] ratio in brain cells. Therefore the following tasks were to be performed: purification from bovine brain, enzymatic characterization, generation of an antiserum and its use for localizing GR in different types of brain cells and search for tissue specific isoforms. The homodimer GR was purified from bovine brain to homogeneity with a specific activity of 145 U/mg of protein and an apparent molecular mass of the subunit of 55 kDa. Simultaneously with GR the cytosolic homotetrameric isoform of malic enzyme was isolated with a specific activity of 40 U/mg of protein and a subunit molecular mass of 64 kDa. In the same way as GR from brain GR from bovine liver was also isolated and with a modificated method also the GR from ox erythrocytes. The specific activites were 147 U/mg and 114 U/mg for the liver and erythrocytes enzymes, respectively. In astroglia-rich and neuron-rich primary cultures from rat brain the presence of the GR was demonstrated by determination of similar specific activities. An antiserum generated against the purified brain enzmye was used for detection of GR in immunoblots and for double-labelling immunocytochemical staining of cultured neural cells. These stainings for GR and cellular markers showed that neurons, microglial cells and oligodendroglial cells strongly express GR, whereas astroglial cells were only weakly stained. Using protein analytical and immunological methods it was difficult to detect differences between the GR preperation from bovine brain, liver and erythrocytes. However mass spectrometric analysis of tryptic peptides of GR from brain and liver detected differences, which could point to the existence of isoforms

Stereoselective synthesis of 2-amino Alcohols from (R)- and (S)-cyanohydrins (Enzyme-catalyzed reactions ; 8)

In der vorliegenden Arbeit berichten wir über die strukturellen Einflüsse auf die Diastereomerenbildung bei der Hydrierung mittels NaBH4 der aus O-Trimethylsilyl-geschützten (R)-Cyanhydrinen mit Grignard-Verbindungen in situ erhaltenen Imino-Verbindungen A zu (1R,2S)-2-Aminoalkoholen. In den zitierten Publikationen werden lediglich Beispiele für (R)-Arylcyanhydrine beschrieben, wobei in der Regel keine optisch reinen (R)-Cyanhydrine eingesetzt wurden und darüber hinaus die erhaltenen Rohprodukte erst durch Umkristallisation gereinigt wurden, so daß korrekte Aussagen über die Diastereoselektivitat der Hydrierung der Imino-Verbindungen A nicht möglich sind.erythro-2-Amino alcohols (1R,2S)- and (1S,2R)-4 may be synthesized stereoselectively by addition of Grignard compounds to cyanohydrins (R)-, (S)-1 and their O-trimethylsilyl derivatives 3, respectively, followed by hydrogenation. The threo-2-amino alcohols (1S,2S)- and (1R,2R)-4 are easily accessible by inversion at C-1 of the (1R,2S) and (1S,2R) compounds

Enantioselective esterification of racemic cyanohydrins and enantioselective hydrolysis or transesterification of cyanohydrin esters by lipases (Enzyme-catalyzed reactions ; 7)

In der vorliegenden Arbeit berichten wir zusammenfassend über die enantioselektive Hydrolyse oder enantioselektive Umesterung racemischer Cyanhydrinester und über die enantioselektive Veresterung racemischer Cyanhydrine mittels Lipasen.Pure cyanohydrin enantiomers (S)-1/(R)-1 and their O-acyl derivatives (R)-3/(S)-3 are obtained from three different lipasecatalyzed reactions: i) enantioselective hydrolysis of aliphatic and aromatic racemic cyanohydrin esters 3, ii) enantioselective acylation of racemic cyanohydrins 1, iii) enantioselective transesterification of 3 with primary alcohols. Both the cyanohydrin esters and the free cyanohydrins (which are prone to racemization) are isolated as enantiomers with high optical purity on a preparative scale. Hydrolysis of the racemic butyrates 3b, e with Candida cylindracea lipase and pseudomonas sp. lipase, respectively, for example, affords the free (S)-cyanohydrins (S)-2-hydroxypentanenitril [(S)-1a] and (S)-mandelonitrile [(S)-1b)] in high yield with 97 and 96% ee, respectively. (S)-1a is obtained with the same optical purity by candida sp. lipase-catalyzed transesterification of 3b with 1-octanol

Decentralised wastewater treatment systems (DEWATS) and sanitation in developing countries: a practical guide

The international discussion about the conservation of water resources and more target-oriented poverty-alleviation strategies creates a favourable environment for new sanitation approaches and innovative wastewater treatment solutions. In many countries, a rapidly upcoming demand for decentralised wastewater treatment systems (DEWATS) and a demand for efficient community-based sanitation (CBS) can be observed. DEWATS is designed to be an element of a comprehensive strategy for city-wide planning and sustainable infrastructure development. In this book, not only are the technical requirements for the efficient treatment of wastewater at a given location explained, but the specific socio-economic conditions and steps for community action planning are also taken into consideration. This book is essential reading for urban service providers (utility managers and employees, governments, regulators, and advisers, urban planners, private sector); national and local government (especially those working with the delivery of urban services); bodies of international co-operation and technical assistance; academic institutions; international NGOs; professional bodies; and local community-based organizations (customer groups, NGOs, CBOs)

Start‐up of a trickling photobioreactor for the treatment of domestic wastewater

A stand-alone trickling photobioreactor (TPBR) was seeded with activated sludge and microalgae to treat domestic wastewater. The TPBR was started-up at 12-h hydraulic retention time at room temperature with 12:12 h light:dark cycle. The light was provided by blue LED strips. The reactor has a total volume of 30 L and is divided into six segments. Each segment is 30 cm long and has a diameter of 15 cm. Each segment was packed with polyurethane foam sponge cubes (2.5 × 2.5 × 2.5 cm3) with 40% occupancy. The chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN), and phosphorus (P) of domestic wastewater varied in the range of 164–256 mg/L, 84.4–133.8 mg/L, 34.2–55.6 mg/L, and 24.7–39.3 mg/L, respectively, during this period. The COD, TOC, TN, and P concentrations in the effluent after 45 days of operation were 30.24 ± 3.36 mg/L, 7.69 ± 0.09 mg/L, 16.67 ± 0.39 mg/L, and 17.48 ± 0.5 mg/L, respectively. The chlorophyll-to-biofilm biomass ratio increased during the experimental period. The above results indicate that the algal–bacterial symbiotic relationship is beneficial for carbon and nutrient removal from domestic wastewater. Practitioner points: Trickling photobioreactor works on natural ventilation and has low power requirements and a small footprint. The porous sponge media helped in immobilizing and subsequent harvesting of biomass. The reactor conditions favored the growth of diatoms (brown algae) over green algae. © 2021 Water Environment Federatio