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USE OF PROTEIN COATINGS ON PIEZOELECTRIC CRYSTALS FOR ASSAY OF GASEOUS POLLUTANTS
No full textPreliminary studies utilizing biological substrates, such as enzymes and
antibodies, as coatings for a piezoelectric crystal detector have proven
successful. Immobilization of cholinesterase and parathion antibodies allows
for the detection of organophosphorous pesticides at the ppb level with the
cholinesterase coatings exhibiting a more specific response to parathion.
Excellent reproducibilities, coating lifetimes, response times and
selectivities are observed. This research is the first use of proteins as
coatings for the direct assay of gaseous compounds, thus making this method an
attractive alternative to some conventional techniques currently in use
ENGINEERING PROTEINS FOR BIOSENSOR APPLICATIONS
No full textThe rapidly developing field of protein engineering will soon make it possible to
tailor the properties of enzymes, antibodies and other proteins for the fabrication
of a new generation of biosensors. Problems which have previously limited the
broader commercial application of biosensors, such as stability and immobilization
efficiency, are likely to be overcome by the successful application of this new
technology. Molecular biologists are now able to rapidly and efficiently alter the
amino acid sequence of any protein for which the gene has been previously cloned or
synthesized. When such changes are based upon detailed knowledge of the threedimensional
atomic structure of the protein and of its biochemical properties, it is
possible to alter both the structure and function of the protein in a rational,
engineering fashion. Early success has already been reported in altering stability,
pH profile, specificity and kinetic parameters. Protein engineering is now also
being used to address the central problem of attaching proteins to the inorganic
components of biosensors in order to enhance our control over the orientation,
arrangement and molecular details of immobilization. When such an approach is
combined with surface chemical modification and monolayer techniques, it should be
possible to achieve far greater control over the critical properties of the interface
between the active protein and the signal transducing portion of the sensor
A MINIATURIZED, PORTABLE ANALYZER FOR OPERATION OF GLUCOSE SENSORS
No full textA glucose monitor system has been developped for use in the fields of
diagnosis and research of diabetes mellitus. This monitor can be used
for continuous measurement of glucose in blood -withdrawn with a
double lumen catheter- as well as in tissue and works in combination
with a specially designed amperometric enzyme sensor
ENZYMATIC ANALYSIS OF TRACE AMOUNTS OF ZINC AND MERCURY
No full textHg * ions can be measured in ultra-trace amounts and in a reproducible manner via an
inhibition of the enzyme activity of alcohol dehydrogenase (YADH; obtained from
yeast).
on7* ions can be measured in pg amounts by using the same enzyme in a stable but inactive
form (Mn2+ in exchange for the cofactor Zn2t) via a reproducible reactivation
of the enzyme activity
PREPARATION AND INVESTIGATION OF ASYMMETRIC BILAYERS ON SOLID SUPPORTS
No full textIn the presented contribution we show thatit is possible to transfer lipid/lipid and lipid/protein
bilayers from fluid or coexisting fluid and solid phases onto solid supports without disarrangement.The
microstrukture ofthelipid films on the air/water interface and the solid substrate can be studiedin detail by
microfluorescence techniques and phase contrast electron microscopy. The methods proposed might be
used in membrane mimetic chemistry for the development of opto-electronic devices and integrated optics,
like evanescentfluorescence and surface plasmon spectroscopy
MICROPERIPHERALS
No full textWe at the VDI/VDE Center for Information Technology promote the
industrial application of research results in the field of
information technology. The Ministry for Research and Technology of
the Federal Republic of Germany has assigned us responsibility for
the following topical areas as part of joint projects which we are
currently conducting in the special field of microperipherals:
Integrated optics and fiber optics for sensor systems
Silicon micromechanics for sensor and actuator engineering
Development of new techniques for surface mounting and interconnections
Technologies for chemical sensor system
STARTER FUR LAGERFAHIGE 1-STUFIGE WEIZENSAUERTEIGE
No full textWheatbreads and rolls without souring baking agents have a self
acid degree (total titrable acid to pH 8.5) about 2 and a pH-value
about 6 units. The addition of sourdough to wheat baking improves
the extensibility of gluten and thus the baking quality. Different
starter cultures without yeast produce different quantities of co,
in the phase of accelerating and exponential growth of bacteria.
These differences depend on the lactic acid cultures. The co,
produced during a stirred fermentation inhibits mould. Different
ash contents of flourtypes induce different acid degrees in
sourdoughs. Acid degrees and ash contents correlate linear in the
range of 0,5 % to 1,7 % ash/drysubstance. Fluid sourdoughs are
longer storable at room temperature than firm ones because they
contain less fermentable carbohydrates. Lactic and acetic acid as
well as ethanol are formated faster. Sourdoughs with a yield of 200 %
contain only a small amount of fermentable carbohydrates. During the
interrupted or retarded fermentation more acid is developped due to
the activity of the lactic acid bacteria, thus the part of sourdough
has to be reduced between 10 % and 20 % from the original formula.
In comparison to conventional produced bakings, wheat sourdough
effects a stronger aromatic flavour. If desired, a sourish taste
is achieved by rising the amount of sourdough. Baking volume and
crumb elasticity of directly produced rolls are equal to sourdough
rolls. Using wheat sourdough it is generally possible to interrupt
the dough fermentation at -7°C or to retard it at +3°C or by
reducing the amount of yeast to 1 %. Formulas for wheat sourdough
processings are available
Einfluß des Drucks auf immobilisierte Enzyme
No full textPressure shows a distinct effect on the activity and stability of enzymes in solution. We
observed for Trypsin an increase of activity of 39,8 % at 55 °C. The investigations were
made continously by using a tubular reactor. Enzymes. immobilized on Eupergit C®, which is
a water-insoluble carrier, behave in a similar manner but with smaller influence of pressure. In opposite to Trypsin in solution, the carrierbound enzyme had a denaturation point of
60 °C (Trypsin in solution: 50 °C). Also the stability rose with pressure. Similar results
were obtained using immobilized Penicillin-Acylase. At 40°C and 300 bar no decrease of
activity could be observed after an incubation time of 2 hours. This high stability leads to to
an increased lifetime of the catalyst which is promotive for technical use
FOLDING OF PEPTIDE FRAGMENTS OF PROTEINS IN WATER SOLUTION: IMPLICATIONS FOR INITIATION OF PROTEIN FOLDING
No full textIt is generally accepted that protein folding proceeds via local
folded intermediates which function as initiation sites for
cooperative growth. However, direct experimental identification of
the transient early folding intermediates of native proteins is
difficult because, under conditions which favor folding, the
polypeptide chain folds rapidly and cooperatively into its native
globular conformation. Recent developments in two-dimensional NMR
spectroscopy have provided very sensitive methods for the detection of
folded structures in peptide fragments of proteins in water solution.
NMR experiments have provided unequivocal evidence for the formation
of #-turns, nascent helix and a-helix in short linear peptides in
water solution. By systematic variation of the amino acid sequence,
information on the factors which stabilize secondary structure in
small linear peptides can be obtained. The observation that peptide
fragments of proteins adopt secondary structures in water solution has
enormous implications for initiation of protein folding, for the
mechanism of induction of protein-reactive anti-peptide antibodies and
for T-cell recognition
DESIGN OF NOVEL INSULINS WITH CHANGED SELF-ASSOCIATION AND LIGAND BINDING PROPERTIES
No full textDifferent wild type insulins have been used for treatment of diabetes mellitus
since Banting and Best (1) isolated insulin for the first time in 1921. This injection
therapy has saved many lives but has not been able to reproduce the serum insulin
profile obtained by physiological endogenous insulin secretion. The requirements
of biosynthesis, processing and storage in the pancreas have put severe constraints
on the insulin molecule giving it properties which are not necessary for the
biological action of the hormone and which limit the possibilities of obtaining adequate
metabolic control in diabetics.The self-association to a hexamer, for example,
facilitates proinsulin conversion and its subsequent precipitation as crystals in the
storage vesicle (2) but is evidently not related to the interaction of insulin as a
monomer to its receptor, and this property delays the transport of insulin from the
subcutaneous depot to the circulation (3).
Thus pancreatie insulin did not evolve for exogenous administration, and with
the aim of producing insulin with improved therapeutical characteristics a whole
series of human insulin analogues with changed self-association and ligand binding
properties has been developed through molecular modelling and recombinant DNA-technology.
Most analogues were designed to have less tendency to associate (4) but a few
were also created to possess stronger association or metal-binding properties