Spectralanalyse des Kadmiums

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Affinity purification of viral protein having heterogeneous quaternary structure: Modeling the impact of soluble aggregates on chromatographic performance

Prokaryote-expressed polyomavirus structural protein VP1 with an N-terminal glutathione-S-transferase tag (GST-VP1) self-assembles into pentamer structures that further organize into soluble aggregates of variable size (3.4 × 10²–1.8 × 10⁴ kDa) [D.I. Lipin, L.H.L. Lua, A.P.J. Middelberg, J. Chromatogr. A 1190 (2008) 204]. The adsorption mechanism for the full range of GST-VP1 soluble aggregates was described assuming a dual-component model [T.Y. Gu, G.J. Tsai, G.T. Tsao, AICHE J. 37 (1991) 1333], with components differentiated by size, and hence pore accessibility, rather than by protein identity. GST-VP1 protein was separated into two component groups: aggregates small enough to access resin pores (LMW: 3.4 × 10²–1.4 × 10³ kDa) and aggregates excluded from the resin pores (HMW: 9.0 × 10²–1.8 × 10⁴ kDa). LMW aggregates bound to resin at a higher saturation concentration (29.7 g L⁻¹) than HMW aggregates (13.3 g L⁻¹), while the rate of adsorption of HMW aggregates was an order of magnitude higher than for LMW aggregates. The model was used to predict both batch and packed bed adsorption of GST-VP1 protein in solutions with known concentrations of HMW and LMW aggregates to Glutathione Sepharose HP resin. Asymmetrical flow field flow fractionation with UV absorbance was utilized in conjunction with adsorption experimentation to show that binding of HMW aggregates to the resin was strong enough to withstand model-predicted displacement by LMW aggregates. High pore concentrations of LMW aggregates were also found to significantly inhibit the diffusion rate of further protein in the resin pores. Additional downstream processing experimentation showed that enzymatic cleavage of LMW aggregates to remove GST tags yields more un-aggregated VP1 pentamers than enzymatic cleavage of HMW aggregates. This model can be used to enhance the chromatographic capture of GST-VP1, and suggests an approach for modeling chromatographic purification of proteins that have a range of quaternary structures, including soluble aggregates.     

Die Vertreibung des kondensierten Wassers bei der organischen Elementaranalyse

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A prime geodesic theorem for SL<Subscript>4</Subscript>

A prime geodesic theorem is derived for rank-one geodesics in quotients of SL₄. This has applications in class number asymptotics for quartic fields. For these applications it is necessary to prove a more general statement than in the literature: several regularity conditions have to be abandoned. As a consequence, the analytical difficulties multiply. The final result is obtained by a sandwiching argument from infinitely many independent asymptotics.     

A dot-blot test using gold colloid cluster technology as a miniaturizable alternative to ELISA and hapten inhibition tests

A novel miniaturizable method to quantify antigens is described in form of a cluster linked immunosorbent assay (CLISA), using inexpensive nitrocellulose (NC) membranes as a support for dot-blotting the antigens. Antibodies for detection are labeled with gold-colloid clusters (GCC). After blocking of the membrane with non reacting protein and application of the GCC-labeled antibodies the signal is detectable by visual colorimetry and can be compared to a color scale prepared from a dilution series of known sample concentrations. The color reaction product is stable for a very long time and does not fade. The sensitivity of the method is comparable to that of ELISA if not better and furthermore needs only small amounts of antibody for detection or for GCC-labeling. This method is an alternative to the use of expensive enzyme-conjugated antibodies for a number of applications, such as tracking of antibodies during purification or hapten inhibition tests. Correspondence: Haifa Al-Dubai, Max F. Perutz Laboratories, Department of Biochemistry, University of Vienna, 1030 Vienna, Austria.     

Der Farbstoff der gelben Dahlien

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Beiträge zur Kenntniss der untersalpetrigen Säure

Ohne ZusammenfassungAn dieser Stelle sei es mir gestattet, Herrn Professor Dr. Gintl für die mannigfache Förderung, welche derselbe mir bei dieser Arbeit zu Theil werden liess, meinen besten Dank auszusprechen. Auch Herrn Docenten L. Storch bin ich für viele werthvolle Rathschläge zu Dank verpflichtet.     

Wiener Chaos and Nonlinear Filtering

The paper discusses two algorithms for solving the Zakai equation in the time-homogeneous diffusion filtering model with possible correlation between the state process and the observation noise. Both algorithms rely on the Cameron-Martin version of the Wiener chaos expansion, so that the approximate filter is a finite linear combination of the chaos elements generated by the observation process. The coefficients in the expansion depend only on the deterministic dynamics of the state and observation processes. For real-time applications, computing the coefficients in advance improves the performance of the algorithms in comparison with most other existing methods of nonlinear filtering. The paper summarizes the main existing results about these Wiener chaos algorithms and resolves some open questions concerning the convergence of the algorithms in the noise-correlated setting. The presentation includes the necessary background on the Wiener chaos and optimal nonlinear filtering.     

Inverse Problem for the Discrete 1D Schrödinger Operator with Small Periodic Potentials

Consider the discrete 1D Schrödinger operator on ? with an odd 2k periodic potential q. For small potentials we show that the mapping: q→ heights of vertical slits on the quasi-momentum domain (similar to the Marchenko-Ostrovski maping for the Hill operator) is a local isomorphism and the isospectral set consists of 2 ^k distinct potentials. Finally, the asymptotics of the spectrum are determined as q→0.