Murein hydrolase (N-acetyl-muramyl-l-alanine amidase) in human serum

An enzyme was identified in human serum which unlike lysozyme cleaved the amide bond between N-acetyl-muramic acid and l-alanine of the peptide side chain of the rigid layer (murein) of Escherichia coli. The N-acetylmuramyl-l-alanine amidase released all of the peptide side chains including those to which the lipoprotein is bound. A portion of the peptide side chains of the Micrococcus lysodeikticus murein was also hydrolysed from the polysaccharide chains. E. coli, M. lysodeikticus, Bacillus subtilis and Staphylococcus aureus were not killed by the amidase. Treatment of E. coli with EDTA or osmotic shock rendered the cells sensitive to the amidase and they were killed. Possible biological functions of the amidase are discussed.The enzyme was separated from lysozyme in human serum. Gel permeation chromatography indicated a molecular weight of the active enzyme of 82,000 while gel electrophoresis in the presence of sodium dodecyl sulfate revealed a molecular weight of 75,000. Thus, the enzyme probably consists of a single polypeptide chain. Incubation with neuraminidase rendered the amidase more basic suggesting the release of sialic acid residues. The modified glycoprotein disclosed an increased activity to murein. Enzyme activity was inhibited by p-chloromercuribenzene sulfonate and ethyleneglycol-bis(2-aminomethyl) tetraacetate (EGTA) at 1 and 0.2 mM concentration, respectively, whereas EDTA up to 5 mM was without effect. The amidase was also inactivated by agents that reduce disulfide bridges.     

An improved method based on the Porter-Silber reaction for determining 17-hydroxycorticosteroids in urine

This paper describes a highly specific method for determining urinary 17-hydroxycorticosteroids, which has been developed by (i) changing the composition of the Porter-Silber reagent and (ii) removing contaminants interfering with the color reaction by addition of sodium bisulfite to β-glucuronidase-hydrolyzed urine before extraction with solvent. For a reference method the Norymberski-Riondel (J. K. Norymberski and A. Riondel 1970, Biochem. J. 120, 493–498) gas chromatography (glc) was used: Correlation coefficient between the present method and GLC = 0.988, deviation from the theoretical regression LINE = 6.8%, and coefficient of SIMILARITY = 0.56. These results are much better than those obtained by I. Ernest, B. Håkansson, J. Lehmann, and B. Sjögren (1964, Acta Endocrinol. 46, 552–562) for the original Porter-Silber method in comparison with the chromatographic measurement of grouped and individual steroids.     

Spruce sugars and poultry hydrolysate as growth medium in repeated fed-batch fermentation processes for production of yeast biomass

Bioprocess and Biosystems Engineering - The production of microbial protein in the form of yeast grown on lignocellulosic sugars and nitrogen-rich industrial residues is an attractive approach for...     

Buchbesprechung (Book Review)

Die Bedeutung insektenpathogener Viren als “Biologische Pflanzenschutzmittel” im System des Integrierten Pflanzenschutzes wird erläutert. Es wird dabei insbesondere auf die “Lückenindikationen” in Kulturpflanzenarten mit geringem Anbauumfang hingewiesen. Zu ihnen werden u.a. Gemüse, Zierpflanzen, Sonderkulturen wie Hopfen, Tabak und Wein, aber auch der Obstbau, gerechnet; daneben gehören aber auch Heil‐und Gewürzpflanzen sowie Rohstoffe für Diät‐und Säuglingsnahrungsmittel dazu. Schließlich wird der Forstschutz als ein wichtiges Refugium für die Anwendung biologischer Pflanzenschutzmittel im allgemeinen und damit auch für insektenpathogene Viren angesehen.

Einen hohen Stellenwert besitzen Unter‐Glas‐Kulturen, da hier biologische Bekämpfungsverfahren schon in einem erheblichen Umfang zur Anwendung kommen.

Die nachfolgenden Beispiele sollen stellvertretend für einen erfolgreichen Einsatz insektenpathogener Viren stehen:

• Bekämpfung von Spodoptera exigua in Chrysanthemenbeständen unter Glas in den Niederlanden mit dem autochthonen Virus und von Mamestra brassicae mit dem spezifischen Kernpolyeder‐Virus in Gewächshauskulturen von Rosen und Paprika (Wirkungsgrad 80 bis 100%) sowie an Kohl im Freiland (Wirkungsgrad 68, 9 bis 100%) in Deutschland.

• Das Granulose‐Virus der Wintersaateule (Agrotis segetum) ergab bei Anwendung gegen den Schädling an Astern Mortalitätswerte zwischen 90, 5 und 94, 1%.

In allen Versuchen erwiesen sich die Viren den als Standard mitgeführten chemischen Insektiziden als gleichwertig.

Am Zusammenbruch lokaler Gradationen der Kiefernbuschhornblattwespe Diprion similis in verschiedenen deutschen Bundesländern (Sachsen‐Anhalt, Sachsen) war ein spezifisches Kernpolyeder‐Virus wesentlich mitbeteiligt.     

Liposomes and Liposome-like Vesicles for Drug and DNA Delivery to Mitochondria

Mitochondrial research is presently one of the fastest growing disciplines in biomedicine. Since the early 1990s, it has become increasingly evident that mitochondrial dysfunction contributes to a large variety of human disorders, ranging from neurodegenerative and neuromuscular diseases, obesity, and diabetes to ischemia-reperfusion injury and cancer. Most remarkably, mitochondria, the “power house” of the cell, have also become accepted as the “motor of cell death” reflecting their recognized key role during apoptosis. Based on these recent exciting developments in mitochondrial research, increasing pharmacological efforts have been made leading to the emergence of “Mitochondrial Medicine” as a whole new field of biomedical research. The identification of molecular mitochondrial drug targets in combination with the development of methods for selectively delivering biologically active molecules to the site of mitochondria will eventually launch a multitude of new therapies for the treatment of mitochondria-related diseases, which are based either on the selective protection, repair, or eradication of cells. Yet, while tremendous efforts are being undertaken to identify new mitochondrial drugs and drug targets, the development of mitochondria-specific drug carrier systems is lagging behind. To ensure a high efficiency of current and future mitochondrial therapeutics, colloidal vectors, i.e., delivery systems, need to be developed able to selectively transport biologically active molecules to and into mitochondria within living human cells. Here we review ongoing efforts in our laboratory directed toward the development of different phospholipid- and non-phospholipid-based mitochondriotropic drug carrier systems.     

Geochemistry and Microbial Populations in Sediments of the Northern Baffin Bay,Arctic

The Northern Baffin Bay between Greenland and Canada is a remote Arctic area restricted in primary production by seasonal ice cover, with presumably low sedimentation rates, carbon content and microbial activities in its sediments. Our aim was to study the so far unknown subseafloor geochemistry and microbial populations driving seafloor ecosystems. Shelf sediments had the highest organic carbon content, numbers of Bacteria and Archaea, and microcosms inoculated from Shelf sediments showed highest sulfate reduction and methane production rates. Sediments in the central deep area and on the southern slope contained less organic carbon and overall lower microbial numbers. Similar 16S rRNA gene copy numbers of Archaea and Bacteria were found for the majority of the sites investigated. Sulfate in pore water correlated with dsrA copy numbers of sulfate-reducing prokaryotes and differed between sites. No methane was found as free gas in the sediments, and mcrA copy numbers of methanogenic Archaea were low. Methanogenic and sulfate-reducing cultures were enriched on a variety of substrates including hydrocarbons. In summary, the Greenlandic shelf sediments contain vital microbial communities adapted to their specific environmental conditions.     

Organic farming affects the potential of a granivorous carabid beetle to control arable weeds at local and landscape scales

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