Fusion of the antiferritin antibody VL domain to barnase results in enhanced solubility and altered pH stability

Chimeric immunotoxins that combine antigen recognition domains of antibodies and cytotoxic RNases have attracted much attention in recent years as potential targeted agents for cancer immunotherapy. In an attempt to obtain a structurally minimized immunofusion for folding/stability studies, we constructed the chimeric protein VL-barnase. The chimera comprises a small cytotoxic enzyme barnase, ribonuclease from Bacillus amyloliquefaciens, fused to the C-terminus of the light chain variable domain (VL) of the anti-human ferritin monoclonal antibody F11. While the individual VL domain was expressed in Escherichia coli as insoluble protein packed into inclusion bodies, its fusion to barnase resulted in a significant ( approximately 70%) fraction of soluble protein, with only a minor insoluble fraction ( approximately 30%) packed into inclusion bodies. The in vivo solubilizing effect of barnase was also observed in vitro and suggests a chaperone-like role that barnase exerted with regard to the N-terminal VL domain. Cytoplasmic VL-barnase was analyzed for structural and functional properties. The dimeric state of the chimeric protein was demonstrated by size-exclusion chromatography, thus indicating that fusion to barnase did not abrogate the intrinsic dimerization propensity of the VL domain. Ferritin-binding affinity and specificity in terms of constants of association with isoferritins were identical for the isolated VL domain and its barnase fusion, and RNase activity remained unchanged after the fusion. Intrinsic fluorescence spectra showed a fully compact tertiary structure of the fusion protein. However, significantly altered pH stability of the fusion protein versus individual VL and barnase was shown by the pH-induced changes in both intrinsic fluorescence and binding of ANS. Together, the results indicate that VL-barnase retained the antigen-binding affinity, specificity and RNase activity pertinent to the two individual constituents, and that their fusion into a single-chain chimeric protein resulted in an altered tertiary fold and pH stability.     

Eigenmoden und Eigenwerte komplementärer sektorförmiger Strukturen: Eine sphärische Multipolanalyse des elektromagnetischen Randwertproblems

Übersicht Mit Hilfe der sphärischen Multipolanalyse werden in dieser Arbeit die E-Moden und die H-Moden sektorförmiger Strukturen bestimmt. Die Lösung des Randwertproblems wird auf die Lösung eines zweiparametrigen Eigenwertproblems mit zwei gekoppelten Laméschen Differentialgleichungen zurückgeführt. Wir leiten eine bemerkenswerte Relation zwischen den Eigenwerten der Eigenmoden komplementärer sektorförmiger Strukturen ab und stellen numerische Ergebnisse vor. Abschließend untersuchen wir die Zusammenhänge zwischen den Eigenmoden komplementärer Strukturen mittels der Babinetschen Transformation.

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Eigenmodes and eigenvalues of complementary sectorstructures: A spherical multipole analysis of the electromagnetic boundary value problem

Contents In this paper the E-modes and H-modes of sectorstructures are determined using multipole expansion. The solution of the boundary value problem is reduced to a two-parametric eigenvalue problem with two coupled Lamé equations. We deduce a remarkable relation between the eigenvalues belonging to the eigenmodes of complementary sector-structures and we present numerical data. Finally, we show the relations between the eigenmodes of complementary structures with the help of Babinet's transformation.

     

Synthesis,Properties and Bioimaging Applications of Silver-Based Quantum Dots

Ag-based quantum dots (QDs) are semiconductor nanomaterials with exclusive electrooptical properties ideally adaptable for various biotechnological, chemical, and medical applications. Silver-based semiconductor nanocrystals have developed rapidly over the past decades. They have become a promising luminescent functional material for in vivo and in vitro fluorescent studies due to their ability to emit at the near-infrared (NIR) wavelength. In this review, we discuss the basic features of Ag-based QDs, the current status of classic (chemical) and novel methods (“green” synthesis) used to produce these QDs. Additionally, the advantages of using such organisms as bacteria, actinomycetes, fungi, algae, and plants for silver-based QDs biosynthesis have been discussed. The application of silver-based QDs as fluorophores for bioimaging application due to their fluorescence intensity, high quantum yield, fluorescent stability, and resistance to photobleaching has also been reviewed.     

Parameterbestimmung bei linearen chemischen Prozessen

Determination of Parameters in Linear Chemical Processes . The authors describe a straightforward and extremely reliable method for determination of the physicochemical parameters occurring in mathematical models of chemical processes. It is based on the restrictive assumption that the system considered is linear and the number of parameters is small. These assumptions permit a detailed eigenvalue analysis of the system, permitting a complete insight into its behaviour. The eigenvalues λ_k and the factors a_k of the corresponding exponential functions are determined by curve fitting. These in turn are determined by system parameters and thus afford relations from which the latter can be calculated. Use of the proposed model requires the design of experiments which can be described by approximately linear models. This is indeed possible in many cases.     

A Library for Self-Adjusting Computation

We present a Standard ML library for writing programs that automatically adjust to changes to their data. The library combines modifiable references and memoization to achieve efficient updates. We describe an implementation of the library and apply it to the problem of maintaining the convex hull of a dynamically changing set of points. Our experiments show that the overhead of the library is small, and that self-adjusting programs can adjust to small changes three-orders of magnitude faster than recomputing from scratch. The implementation relies on invariants that could be enforced by a modal type system. We show, using an existing language, abstract interfaces for modifiable references and for memoization that ensure the same safety properties without the use of modal types. The interface for memoization, however, does not scale well, suggesting a language-based approach to be preferable after all.     

Effect of riboflavin treatment on human red cell pyruvate kinase deficiency

The effect of riboflavin on six patients with hemolytic anemia due to hereditary pyruvate kinase deficiency was studied. Treatment over a period of four to six months produced no significant hematologic or enzymologic changes in the variants investigated.     

Flame temperatures and species concentrations in non-stoichiometric oxycoal flames

The oxyfuel technology offers the possibility for CO₂ sequestration from coal fired power plants. One drawback is the need for a high external flue gas recirculation to avoid inadmissible high flame temperatures. The concept of controlled staging with non-stoichiometric burners (CSNB) allows a significant reduction of the commonly proposed flue gas recirculation rate while fulfilling all requirements on temperature limitations. The concept aims at a more efficient oxyfuel process with a higher degree of freedom for heat-flux adjustments suitable for a new generation of oxyfuel boilers. The steam generator size could be reduced and in this way a more cost effective steam generator concept is possible. Additionally the energy demand for the flue gas recirculation is lowered.This paper presents the experimental investigations of non-stoichiometric oxycoal flames. Temperature and gas profiles were taken to analyze the combustion behavior of coal with high oxygen concentrations in the oxidizer under oxygen deficiency and accordingly oxygen excess. In addition an optical flame monitoring system allowed a comparison of ignition, flame shape and stability. In the test rig lignite was burned under different stoichiometries ranging from 0.5 to 2.5 and different oxygen concentrations in the oxidant ranging from 30 to 40 vol.%. The thermal input of the burner was 70 kW at a total thermal input of 140 kW and a dry flue gas recirculation was used. The results were compared to a conventional air-blown combustion and showed that similar temperature ranges can be reached even with oxygen concentrations in the oxidizer as high as 40 vol.%.