Oberflächen-Plasmon-Resonanz- spektroskopische Studie an verschiedenen Biosensoroberflächen. Charakterisierung von Protein-Peptid und Protein-Lipid Wechselwirkungen

Surface plasmon resonance spectroscopy (SPR spectroscopy) is a technique for the time-resolved measurement of interactions between macromolecules. For thesemeasurements, it is necessary to immobilize a binding partner on the surface of asensor chip. The measurements are recorded as sensorgrams. In the present study,different surfaces were tested. The biological model system for the investigation ofinteractions was the binding of calmodulin to a synthetic peptide which correspondsto the amino-acid sequence of the CaM binding site from the typed nitrogen oxidesynthase. For binding CaM to this peptide, NOS-I WT, the rate constants (k$_{a}$, k$_{d}$) andthe equilibrium constants (KD) were determined by different evaluation methods.The dissociation constants determined from the sensorgrams for the different sensorchip surfaces increased with rising immobilization density. An analysis of the rateconstants determined from the sensorgrams showed that especially k$_{a}$ decreasedsubstantially with increasing immobilization density. The sensorgrams on the differentsensor surfaces could no longer be explained by a monoexponential bond model athigh immobilization density. This was also reflected in the decreasing stoichiometryof peptide NOS-I WT for CaM at increasing immobilization density of the peptide. Thebest agreement with the literature values achieved on a dextran surface at very lowimmobilization density (< 5.8 fmol/mm$^{2}$) on peptide NOS-I WT (K$_{D}$ values of 0.8 - 3.9nM).Furthermore, sensor chips with hydrophobic surfaces were produced to build upheterobilayers or phospholipid bilayers. These sensor chips were used to investigatethe Ca$^{2+}$-dependent membrane association of the Ca$^{2+}$ binding protein recoverin. AnN-terminal myristoyl group anchors recoverin at high calcium concentrations in themembrane. Mutants of recoverin were examined, whose affinities for Ca2+ ions weremodified in comparison to the wild type. All forms of recoverin (native, recombinantlymyristoylated (WT), EF+4, EF-3, EF-2) show a bond to the hydrophobic sensor chipsurface in the presence of Ca$^{2+}$ ions, although with different affinities (EC$_{50}$: nativerecoverin = 18 $\mu$M; WT = 5 $\mu$M; EF+4 = 29 $\mu$M; EF-3 = 8 $\mu$M; EF-2 = 9 $\mu$M).Interestingly enough, it was also possible to detect a bond to the phospholipid layerin the absence of Ca$^{2+}$ which, however, occurred with a markedly lower amplitude

Measuring Competition in the U.S. Airline Industry Using the Rosse-Panzar Test and Cross-Sectional Regression Analyses

We employ the Rosse-Panzar test to assess market performance in selected airport-pairs originating from Atlanta. The Rosse-Panzar test stands in the tradition of the New Empirical Industrial Organization. It is based on the comparative statics of a reduced form revenue equation. Therefore, it is less powerful than structural models, but it offers the advantage of less stringent data requirements and reduces the risk of model misspecifications. The test statistic allows us in most airport-pairs to reject both conducts consistent with the Bertrand outcome, which is equivalent to perfect competition, and the collusive outcome, which is equivalent to joint profit-maximization. Rather, the test statistic suggests that behavior is consistent with a range of intermediate outcomes between the two extremes, including, but not limited to the Cournot oligopoly. In the second part of the paper, a cross-section pricing regression complements the Rosse-Panzar test. It shows that the presence of low-cost competition in an airport-pair reduces the average fare significantly.airlines; oligopoly; conduct; price-cost marginas; Lerner index; Rosse-Panzar test

Comparison between the regression depth method and the support vector machine to approximate the minimum number of misclassifications

The minimum number of misclassifications achievable with afine hyperplanes on a given set of labeled points is a key quantity in both statistics and computational learning theory. However, determining this quantity exactly is essentially NP-hard, c.f. Simon and van Horn (1995). Hence, there is a need to find reasonable approximation procedures. This paper compares three approaches to approximating the minimum number of misclassifications achievable with afine hyperplanes. The first approach is based on the regression depth method of Rousseeuw and Hubert (1999) in linear regression models. We compare the results of the regression depth method with the support vector machine approach proposed by Vapnik (1998), and a heuristic search algorithm

Photochemische und biochemische Modifikation von Bakteriorhodopsin: Optische Datenspeicherung und Hybridbio-Materialien

Entwicklung und Evaluierung einer auf Bakteriorhodopsin (BR) basierenden photochromen Tampondruckfarbe. Untersuchungen an neuen langzeitstabilen Photoprodukten von BR und Entwicklung eines biologisch-optischen WORM Datenspeichers und einer Datenchiffriermethode. Etablierung von MS- und LC/MS/MS-Methoden zur Untersuchung von biochemisch-modifiziertem BR. Entwicklung einer universellen Methode zur reversiblen Anbindung von Bionanokomponenten an BR. Etablierung einer Methode für die gerichtete Selbstassemblierung von Purpurmembranfragmenten auf Template-Stripped-Gold-Substraten

QCD's equation of state from Dyson-Schwinger equations

In this contribution, we summarize a truncation-independent method to compute the equation of state within nonperturbative functional approaches. After demonstrating its viability, the method is applied to solutions obtained from a set of truncated Dyson-Schwinger equations for the quark and gluon propagators of (2+1)-flavor QCD to obtain thermodynamic quantities across the phase diagram of strong-interaction matter.Comment: 6 pages, 2 figures; contribution to the proceedings of the FAIR next generation scientists workshop (FAIRNESS), 7th edition, 23-27 May 2022, Paralia (Pieria), Greec

Low cycle fatigue testing in high pressure gaseous hydrogen using tubular specimens

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