What to Learn from a Comparative Genomic Sequence Analysis of L-Carnitine Dehydrogenase

In contrast to eukaryotic cells certain eubacterial strains have acquired the ability to utilize L-carnitine (R-(–)-3-hydroxy-4-(trimethylamino)butyrate) as sole source of energy, carbon and nitrogen. The first step of the L-carnitine degradation to glycine betaine is catalysed by L-carnitine dehydrogenase (L-CDH, EC 1.1.1.108) and results in the formation of the dehydrocarnitine. During the oxidation of L-carnitine a simultaneous conversion of the cofactor NAD⁺ to NADH takes place. This catabolic reaction has always been of keen interest, because it can be exploited for spectroscopic L-carnitine determination in biological fluids – a quantification method, which is developed in our lab – as well as L-carnitine production.Based on a cloned L-CDH sequence an expedition through the currently available prokaryotic genomic sequence space began to mine relevant information about bacterial L-carnitine metabolism hidden in the enormous amount of data stored in public sequence databases. Thus by means of homology-based and context-based protein function prediction is revealed that L-CDH exists in certain eubacterial genomes either as a protein of approximately 35 kDa or as a homologous fusion protein of approximately 54 kDa with an additional putative domain, which is predicted to possess a thioesterase activity. These two variants of the enzyme are found on one hand in the genome sequence of bacterial species, which were previously reported to decompose L-carnitine, and on the other hand in gram-positive bacteria, which were not known to express L-CDH. Furthermore we could not only discover that L-CDH is located in a conserved genetic entity, which genes are very likely involved in this L-carnitine catabolic pathway, but also pinpoint the exact genomic sequence position of several other enzymes, which play an essential role in the bacterial metabolism of L-carnitine precursors.     

Das ultrarote Absorptionsspektrum des Natriumnitrats

Zeitschrift für Physik A Hadrons and nuclei - Es wird auf einen Fehler in Oppenbeimers kürzlich veröffentlichter Arbeit hingewiesen. Wenn die Energien des Elektrons vor und nach der...     

Ueber das Atomgewicht des Nickels und Kobalts und eine Neubestimmung des Atomgewichts des Eisens

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A new enzyme catalysis: 3,4-dioxidation of some aryl β-d-glycopyranosides by fungal pyranose dehydrogenase

Quinone-dependent pyranose dehydrogenase presents a new tool for versatile conversions of numerous carbohydrates to their di- and tricarbonyl derivatives. This enzyme purified from the basidiomycete Agaricus meleagris catalysed dioxidation of several aromatic β-d-glucopyranosides and a β-d-xylopyranoside into the corresponding 3,4-didehydro-β-d-aldopyranosides (β-d-aldopyranosid-3,4-diuloses) in high yields, typically >80% for 4-nitrophenyl glycosides. These new compounds were doubly hydrated in aqueous solution. According to in situ NMR investigations, the reaction intermediates were the corresponding 3- and 4-dehydro compounds. The analogous anomeric α-glycosides underwent one-step oxidation only at C-3 to 3-dehydro-α-d-aldopyranosides (α-d-pyranosid-3-uloses).     

Zur Elementaranalyse stickstoffhaltiger K?rper

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Zur Entwicklung von Chlorgas

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