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SIMPLIFIED DETECTION OF BIOLOGICAL HALOGENATION AND DEHALOGENATION WITH A HALIDE SENSOR
No full textFlow injection analysis of halides with a halide selective electrode is a
sensitive method to follow changes of halide concentrations which
accompany biological halogenation and dehalogenation reactions. Less than
10 picomole chloride or 2 picomole bromide can be detected. At low halide
concentrations the halide concentration and the potential change correlate
linearily
Culture Fluorescence Studies for Process Monitoring and Control in Biotechnology
No full textEfficient "control of biological processes requires che
measurement of various biological parameters. The on-line
measurement of NADH- dependent culture fluorescence gives a
direct insight into the microorganisms during cultivation. A
miniaturized microfluorometer with special fibre optics for
the simultaneous detection of two different wavelengths was
constructed and applied for process monitoring. In addition
an Ingold prototyp fluorometer ( Dr. Ingold AG, Switzerland)
was also studied
Formation of Supported Lipid / Protein Bilayers by Surface Induced Vesicle Fusion
No full textFor certain applications in biosensor technology it is necessary to coat the
sensor surface with a reconstituted lipid / protein membrane. Here a new technique is
presented which, in contrast to the Langmuir-Blodgett- technique, allows the self
assembly of supported bilayers from the aqueous phase by surface induced vesicle
fusion. This paper is focussed on the formation process but gives also a detailed
characterization of the physical properties of the resulting susported bilayers, as well as
an analysis of the stability of these membranes for various supports
CHEMICALLY MODIFIED ELECTRODES AS BIOSENSORS: AMPEROMETRIC GLUCOSE SENSOR FOR FLOW INJECTION ANALYSIS
No full textAn amperometric biosensor was constructed for glucose blood serum
determinations with flow injection analysis. A platinized, reticulated
vitreous carbon (RVC) electrode is used as an enzyme support, reactor,
and detector. A partial platinum coating provided an increased current
response from the oxidation of hydrogen peroxide, as compared with a
bare RVC electrode. It also allowed the electrode to operate at a much
lower potential (+0.6 vs +0.9 volts vs SCE), thus resulting in an
increased signal to noise ratio. However, carbonaceous sites were still
available for enzyme immobilization. Glucsseloxidase (E.eC2 1T.1IE 3.4) is
immobilized on the surface of the RVC electrode to provide selectivity
for glucose and to produce an electroactive product, hydrogen peroxide.
The enzyme is immobilized by either covalent attachment with
carbodiimide or cross-linking with glutaraldehyde. The enzyme remained
active for over three months with almost daily use. An
electropolymerized film of 1,2-diaminobenzene was incorporated on the
sensor to eliminate the effects of electrochemically active
interferences present in serum samples. The polymer film also virtually
eliminated electrode fouling caused by large proteins. The working
lifetime of the sensor, as well as, the thermal stability of the
immobilized glucose oxidase were increased by the polymer film
STUDIES OF CLINICAL ISOLATES OF FLAVOBACTERIA
No full textComputer analysis was used in a numerical taxonomy study of flavobacteria from
clinical, environmental, and marine sources. The 138 strains examined included
representatives of the Center for Disease Control (CDC) groups Ila, IIb, and IIf.
None of the marine strains was similar to those of clinical origin. The largest
group, IIb of the CDC and Group O of McMeekin, appeared to merit recognition as a
named species. Group Ila ( Flavobacterium meningosepticum) was similar to group
IIb, and was antigenically related to group IIf
THE CYTOPHAGA-LIKE BACTERIA: A SEARCH FOR KEY CHARACTERS
No full textNearly 800 Cytophaga-like bacteria (CLB) were isolated from soil and freshwater.
Mainly out of these isolates, 185 strains were chosen for a phenotypic analysis, employing
130 different tests. The aim was to find specific traits that would lead to
a reasonable clustering and thus could be used as taxonomical key characters. An apparently
reasonable classification was obtained with the following characters: gliding
motility,cell morphology, cellular shape-change, presence of flexirubin-type
pigments and of certain enzymes (catalase, cytochrome oxidase, lecithinase, urease,
phenylalanine deaminase, DNase, starch hydrolysis, and gelatin liquefaction). The
characters were weighted and used in the order given above. Obviously, this chosen
hierarchy has an influence on the resulting arrangement of the strains. Nonetheless,
it was possible to define certain groups quite reliably, such as Flexibacter and
Lysobacter. However with other groups, particularly with subgroups, results were often
ambiguous. A comparison with data obtained by DNA/DNA hybridization /4/ suggests,
that for the different groups and subgroups of CLB different sets of key characters
have to be applied, or that at least the hierarchy of the characters has to be altered
Title, Preface, Contents, Contributors
No full textPreface
Subtle and specific recognition between complex macromoleculesis at the core of virtually
every life process. Knowledge about the chemical nature of these interactions is
rapidly increasing at present. From the beginning, synthetic organic chemistry has
been an important tool in the acquisition of this knowledge, the elucidation of the
genetic code being the most dramatic example of the contributions chemists have
madeto biology.
A decade ago, the advent of genetic engineering opened up newhorizonsto the nucleic
acids or protein chemist. With the techniques of molecular cloning at hand one
could for thefirst time in history select individual molecules from synthetic mixtures
andin principle prepare unlimited amounts of chemically homogeneous macromolecules.
Today, we have just begun to see someofthe far-reaching consequencesof
this revolutionary development.
Yet, molecular cloning hasits limitations: in planning a synthesis, one is in practice
constrained to the naturally occurring monomersof nucleic acids and proteins. Often
however, one would like to introduce a non-natural monomerunit into a nucleic acid or
protein molecule to study, for instance, the effect of an individual functional group ona
biological process. In such studies, the biochemisthasto rely again on his classicalorganic-
synthetic repertoire exclusively.
Beyond theintroduction of functional groups that exceed the repertoire of natural nucleosides
and amino acids, post-translational protein modifications such as the addition
of oligosaccharide side chains, are an additional area of great interest that is not
easily accessible by genetic engineering.
In this book wehavetried to bring together a number of examplesillustrating the importance
of organic synthesis for contemporary molecular biology in different areas of
interest. These include
— Synthesis of nucleic acids that cannot be amplified by molecular cloning and their
application in studying processes of mutagenesis/carcinogenesis and DNA-protein
interaction
— DNAsynthesis and genetic diagnosis
— Protein design
— Chemical peptide synthesis in the developmentof vaccines
— Cell-surface oligosaccharides and cell-cell interactions
The book evolved from a symposium weorganized and held in Braunschweig in September
1984 with the aim of bringing together a set of leading specialists in diverse
fields and initiating an interdisciplinary exchange of views and ideas. Thus the bookreflects
the individual blend of this symposium — no attempt at a comprehensive review
has been made.
Wethank the sponsorsof the meeting, Stiftung Volkswagenwerk, Fonds der Chemischen
Industrie and Bundesministerium für Forschung und Technologie. Our special
thanks go to the symposium speakers and chairmen, and the contributors to this
book
CLEAVAGE OF PHOSPHOROTHIOATE-CONTAINING OLIGONUCLEOTIDES AND DNA BY RESTRICTION ENDONUCLEASES
No full textThe oligonucleotide d(GGsAATTCC) containing the recognition sequence of the Eco
R1 restriction endonuclease with a phosphorothioate group at the site of cleavage was
synthesized by two approaches both based on the polymer support phosphoroamidite method.
Only the Rp-diastereomer was cleaved by Eco R1, at a rate approximately 20 times
slower than the all-phosphate-containing octamer. To study the interaction of restriction
endonucleases with phosphorothioate internucleotidic linkages double stranded
Mi3mp2 DNA was prepared in which the (+)strand contained only phosphate groups but
the (-)strand phosphate groups as well as base specifically introduced phosphorothioate
groups of the Rp-configuration. This hybrid DNA was cleaved by several restriction
enzymes. The results obtained allow the classification of these enzymes into three
groups: those which produce nicked DNA as an isolatable intermediate, those where the
nicked DNA is the final product and a third where only linearised DNA can be detected.
Particularly the second class of enzymes should be of interest for the manipulation
of DNA
Titel, Vorwort, Inhalt, Verzeichnis der Autoren
No full textAuf der Grundlage der Polymerchemie hat die Membranforschung in den letzten beiden
Jahrzehnten rasche Fortschritte gemacht. Die an Membranen mégliche Trennung
gasformiger, fester oder geléster Stoffe hangtim Einzelfall stark von den stofflichen Eigenschaften
der zu verarbeitenden Gemische ab. Dazu kommt eine komplexe Wechselbeziehung
zwischen den Stoffeigenschaften, Membraneigenschaften und den Betriebsbedingungen,
die eine Voraussage Uber Kosten und Wirtschaftlichkeit von Verfahrensvorschlagen
sehr erschweren.
In der Biotechnologie gibt es ganz unterschiedliche Einsatzmöglichkeiten von technischen
Membranen. Zum einen sucht man nach Methoden für die Zellkultivierung,
Stoffproduktion und Aufarbeitung im geschlossenen System, die eine sterile und sichere
Betriebsweisebei selektiver Durchlässigkeit für bestimmte Stoffe erlauben. Andererseits
stehen die schonende Behandlung labiler Produkte im Prozeß und die energiegünstige
Abtrennung von Wasser im Vordergrund des Interesses. Während beispielsweisedie
Ultrafiltration zur Konzentrierung von Proteinen oderdie Mikrofiltration
zur Abtrennung von mikrobiellen Kontaminantionen aus Lösungenbereits zum etablierten
Stand der Technik gehören, befinden sich andere Membranverfahren in biotechnologischen
Prozessen noch in der Entwicklung oder zeichnen sich in der Forschungab.
Diese Themen standen im Mittelpunkt einer zweitägigen Arbeitstagung der GBF im
Mai 1985. Ausihr sind die Beiträge des vorliegenden Bandes hervorgegangen. Das
große Interesse an dieser Tagung sowohl von seiten der Membranhersteller und Ap- |
paratebauer als auch bei den immer zahlreicher werdenden Anwendern und For- i
schern in der Industrie und an den Hochschulen spiegelt die Dynamik der Situation
und den weit verbreiteten Wunsch nach einer zusammenfassenden Diskussion wider.
Dazu gaben die Tage in Braunschweig vielfaltige Gelegenheit und Anregungen. Die
hier vorgelegten Beitrage sollen die Information und die Diskussion zum Nutzen der
Biotechnologie weitertragen. I
An dieser Stelle möchten wir Herrn Dipl.-Ing. Karl Heinz Kroner für seine Unterstützung
in der Organisation der Arbeitstagung und Herrn Dr. Johann-Heinrich Walsdorff für
seine Hilfe bei der Herausgabe dieses Berichtsbandes herzlich danken
PEG-NAD* IN AMPEROMETRIC DEHYDROGENASE ELECTRODES WITH COENZYME RECYCLING
No full textA new method for the synthesis of PEG-NAD* via activation of PEG
with carbonyldiimidazole is described; a very stable non-dialysable
and biologically active coenzyme derivative is obtained. In compact
amperometric dehydrogenase electrodes this coenzyme derivative,
physically entrapped with the dehydrogenase and placed in proximity to
a modified graphite electrode surface, leads to enzyme deactivation
and extraction of the catalyst. Therefore electrodes with low response
and short lifetime result. In addition the response of these
electrodes is dominated by the very high diffusion coefficient and the
high viscosity of its solution. Possibilities to overcome these
problems are discussed