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STUDIES ON THE DEGRADATION OF CELLULOSE BY SPOROCYTOPHAGA MYXOCOCCOIDES
No full textCulture fluids of Sporocytophaga myxococcoides contain extracellular enzyme activ+
ties capable of hydrolysing cellulose, carboxymethylcellulose and cellobiose. The
yield of enzyme activities varies with the nature of the organism's carbon source and
glucose is apparently an inducer. There is no detectable glucanase capable of hydrolysing
-nitropheny] glucoside in these preparations. Supernatants of cellulose
grown cells do not contain any detectable glucose or cellobiose. Such supernatants
contain, in addition to cellulose, an unidentified reducing compound and no other
detectable non-ionic carbon compounds. The reducing compound functions as a linking
metabolite in the growth of a non-cellulolytic Alcaligenes sp. that is capable of
growth in mixed culture with S. myxococcoides using cellulose as sole source of
carbon and energy
PROTEIN-DNA RECOGNITION: THE INTERACTION OF Jac, cI AND Z. coli RNA POLYMERASE WITH OPERATORS AND PROMOTERS
No full textCurrent methods for synthesizing DNA utilize protected deoxynucleoside
phosphoramidites as synthons and a glass or silica gel solid support as the
synthesis matrix. Syntheses are extremely rapid (5-10 minutes per cycle) and lead
to high yields of deoxyoligonucleotides containing 20-100 mononucleotides each.
Using these methods to synthesize modified DNAs, the interaction of Z. coli RNA
polymerase and cI repressor with lambda Pp promoter has been studied. Results
identify certain 5-methyl groups located in the -35 region of the promoter and Opl
that are important protein recognition sites. These results correlate quite nicely
to previous research with Jac repressor. Additional data suggest possible
insights regarding the formation of open promoter complexes
BIOTINYLATED OLIGONUCLEOTIDE HYBRIDIZATION PROBES: PROGRESS TOWARDS A NON-RADIOACTIVE METHOD FOR THE DIAGNOSIS OF HUMAN GENETIC DISEASES.
No full textUnder appropriate conditions synthetic oligonucleotide hybridization
probes display essentially absolute hybridization specificity. All of the
non-Watson-Crick base pairs, including G-T, have a destabilizing effect.
Thus, it is possible to choose stringent conditions of hybridization such
that, while a perfectly matched duplex between an oligonucleotide and
complementary DNA will form, duplexes mismatched at one or more
positions will not. The hybridization of oligonucleotides to regions of
DNA containing the single base changes responsible for many human genetic
disease, thus, provides a means of detecting these diseases.
In an attempt to develop a non-radioactive method for the detection of
human genetic diseases, we have prepared biotinylated oligonucleotides by
an enzymatic method. An oligonucleotide probe (23-mer) containing a
single biotinylated deoxyuridine residue at the 3’-terminus was prepared
by a primer extention reaction using E. coli DNA polymerase I (Klenow
fragment). The biotinylated probe could be hybridized to a complementary
sequence and visualized by Avidin D and biotinylated alkaline phosphatase.
A general approach to the enzymatic synthesis of oligonucleotides containing
a single biotinylated deoxyuridine at the 3’ end is described
L-AMINOSÄURE-PRODUKTION IM ENZYM-MEMBRAN-REAKTOR
No full textIn einer Enzym-Membran-Reaktor-(EMR)-Anlage in Konstanz werden die
L-Aminosäuren Methionin, Phenylalanin und Valin durch Acylasekatalysierte
Racematspaltung aus den entsprechenden Acety1-0,Laminosäuren
mit einer Jahreskapazität von insgesamt mehr als 200
Tonnen produziert.
In Labor- und Pilotversuchen konnten im Enzym-Membran-Reaktor weitere
Systeme, wie die Fumarase-katalysierte L-Apfelsaure-, die Aspartasekatalysierte
L-Asparaginsäuregewinnung sowie die NADH-abhängige durch
entsprechende Dehydrogenasen katalysierte Umwandlung von a-Keto-,
bzw. a-Hydroxycarbonsäuren in L-Aminosäure mit Erfolg getestet
werden.
Für die Rückhaltung der Enzyme eignen sich in der Regel Kapillarmembranen
mit einer Ausschlußgrenze von 10.000 Dalton; bei Einsatz
des am Polyethylenglycol 20.000 gebundenen Coenzyms NADH sind Flachmembranen
(5.000 Dalton) vorteilhafter
KINETISCHE INSTABILITÄT IM GEKOPPELTEN ENZYMSYSTEM - DARGESTELLT AM BEISPIEL DER ENZYMKATALYSIERTEN L-PHENYLALANIN-HERSTELLUNG IM ENZYM-MEMBRAN-REAKTOR
No full textMehrfach-stationäre Zustände sind bei Ein-Enzym-Systemen nicht unbekannt; in der Literatur
ist bisher jedoch nicht beschrieben, daß solche Effekte auch in gekoppelten Enzymsystemen
möglich sind. Am Beispiel der enzymkatalysierten Gewinnung von L-Phenylalanin
im Enzym-Membran-Reaktor soll gezeigt werden, daß unter bestimmten Bedingungen
auch im gekoppelten Zwei-Enzym-System mehrfach-stationäre Zustände auftreten können.
Enzyme, die durch einen Überschuß an Substrat inhibiert werden, können im kontinuierlich
betriebenen Rührkessel (CSTR) das Auftreten von mehrfach-stationären Zuständen
bewirken /1/. Substratüberschußinhibierungen führen dazu, daß unter Anfangsreaktions-
Geschwindigkeits-Bedingungen Reaktionsgeschwindigkeits-Maxima als Funktion der Substratkonzentration
durchlaufen werden. Sehr oft werden diese Enzyme zusätzlich durch
eines oder mehrere ihrer Reaktionsprodukte inhibiert. Das gleichzeitige Auftreten von
Substratüberschuß und Produktinhibierung mündet häufig in eine pseudo Michaelis-Menten-
Kinetik, womit mehrfach-stationäre Zustände unwahrscheinlich werden
ELECTROCHEMICAL SENSORS FABRICATED BY MICROELECTRONIC FABRICATION PROCESSES FOR THE DEVELOPMENT OF BIOSENSORS
No full textMany electrochemical sensors have found direct applications as biomedical
sensors, such as blood gas e.g. PO), pH and PCO» sensors. In addition,
electrochemical sensors are an integral part of other biomedical sensors; a typical
example being the polarographic oxygen sensor based glucose sensor.
Microelectronic fabrication technology has been demonstrated to be a good means to
produce low-cost, reproducible, small scale electronic devices. These technologies,
such as thick and thin film deposition, photolithographic reduction, and chemical
and plasma etching, permit well-delineated patterning of metallic, insulating and
semiconducting surface layers. Consequently, highly uniform, geometrically welldefined
and identical metallic or other surface areas can be produced. This high
degree of reproducibility of the geometry of the electrode surface area is unique
and important in sensor development. The attractive features of this fabrication
technology are well-suited to the development of various electrochemical sensorbased
biosensors, particularly for amperometric electrochemical sensor-based
devices. Microelectronic fabrication techniques have the capacity to produce small
size, relatively low-cost biomedical sensors. Furthermore, arrays of identical or
different electrochemical sensors can be produced with relative ease, enhancing the
reliability, repeatability and versatility of the sensors. New sensor operational
methodology may also be exploited. Examples of the fabricated sensors will be used
to illustrate the potential advantages of this approach. The present limitations of
this fabrication technique will also be assessed
OPTICAL PRESSURE MEASUREMENTS FOR BIOLOGICAL APPLICATIONS
No full textExtrinsic fiber optic pressure transducer (optode) development has progressed from
the use of bifurcated bundles, to dual-fiber configurations, and recently to singlefiber
optodes. Pressure optodes are used in biomedical applications because of the
advantages (electrical isolation of the patient, immunity to electromagnetic fields
and small size) they offer over older, electrically based measurements. It is also
possible to use intrinsic fiber optic sensors, based on pressure-induced changes in
in the fiber itself, to make distributed sensing systems
BIO-IMAGING SENSOR SYSTEM FOR CANCER CELL DETECTION
No full textNovel cytorecognition method using two-dimensional imaging sensor system and
monoclonal antibodies has been developed. The method based onan immunofluorescence
was very sensitive. The system could also been applied for the determination of
cell-surface antigens and tumor cells infiltrated in a tissue
HINWEISE AUF DIE URSACHEN FUR DIE ANREICHERUNG VON LEUCIN, ALANIN, PHENYLALANIN UND TYROSIN UNTER DEN FREIEN AMINOSÄUREN DES FERMENTIERTEN KAKAOS
No full textThe composition of free amino acids in fermented cocoa beans and of cocoa seeds after
fermentation-like incubations has been determined by RP-HPLC. Leucine, alanine,
phenylalanine and tyrosine dominate by far. The total seed protein consists of
significantly less of these four hydrophobic amino acids and contains more of the
acidic amino acids. Three explanations are given which are supported by preliminary
experimental results: 1. The vacuolar storage protein which is hydrolized during
fermentation is enriched in these hydrophobic amino acids. 2. Free acidic amio acids
are metabolized in the seed before onset of postmortem proteolysis. 3. Cocoa seed
endopeptidases are aspartic acid proteinases. This type of enzyme gives rise to
peptides with hydrophobic amino acids in the terminal positions which are the first
to be attacked by exopeptidases
PROZESSENTWICKLUNGFUR DIE SCHNELLE REINIGUNG DER ASPARTASE AUS ESCHERICHIA COLI K 12
No full textDie Aspartase von E. coli K 12 wurde durcheinen verbesserten Aufarbeitungsprozeß aus dem
hochproduzierenden Stamm JRG 1849 isoliert (1), der das Asp-Gen auf einem MulticopyPlasmid trägt.Das schnelle Reinigungsverfahren besteht aus 2 Flüssigextraktions-(2,3) und zwei
Chromatographie-Schritten und kann innerhalb eines Tages durchgeführt werden. Nach der
SDS-PAGE (Silber-Färbung) ist die Enzympräparation homogen. Von dieser homogenen
Enzympräparation konnten nach der "hanging drop"-Methode reproduzierbare Kristalle (0.1 x
0.5 mm) erhalten werden. Das Reinigungsverfahren erlaubt ein unproblematisches Scale-up
und erscheint besondersfür die semikontinuierliche Prozeßführung geeignet