High reproducibility of large-gel two-dimensional electrophoresis

Two-dimensional gel electrophoresis (2-DE) facilitates the separation of thousands of proteins from highly complex protein mixtures and has become a central method in proteomics in recent years. In the present study, we examined the technical variability of large 2-DE gels with respect to sample preparation, electrophoresis procedure, data acquisition, and biological variation by analyzing a disease (Huntington's disease) and control state with a commercially available software package, PROTEOMWEAVER trade mark. Scatter plots and correlation coefficients were obtained to quantify both technical and biological variation. Even 2-DE gels run separately in both dimensions yielded correlation coefficients around 0.88 and deviations from the mean close to 20% for low-intensity spots. This indicates a high technical reproducibility of the 2-DE procedure developed in our laboratory. Variability within a biological condition was low and comparable to technical variation (at least 0.87). Two-dimensional (2-D) gels obtained from samples of different biological conditions (health vs. disease) achieved a variability similar to intracondition and technical variability. These findings highlight the importance of multiple gel and spot-by-spot comparisons to identify biological significant changes. Minor errors introduced by technical and biological variation allow a comparison of all gels within a study which facilitates the tackling of complex biological problems.     

Quantification of transients using empirical orthogonal functions

The method of empirical orthogonal functions (EOFs) is used to analyse spatio-temporal data obtained from simulations of heterogeneous catalysis. It is found that EOFs are well suited for the quantitative determination of transients in the data. The effectivity of the technique is demonstrated using synthetical data with an analytically known transient component.     

Refined quantum chemical calculations of deuterium quadrupole coupling constants and their contribution to the resolution of experimental ambiguities

Previously, a special basis set for the ab initio SCF calculation of deuterium quadrupole coupling constants was developed. Here it was applied to the acetylenes DCCH, DCCCH₃, DCCCl, DCCF, and DCCCN to resolve an experimental ambiguity. The calculated values are consistently larger than the experimental values by about 10 kHz but are otherwise in good agreement, except for the case of a beam maser measurement for DCCCH₃ which should be checked.     

Near-Hartree-Fock energies and geometries of the hydrogen clusters H n + (n(odd) ≤ 13) obtained with floating basis sets

The H _n ⁺ clusters,n (odd) ≤ 13, are used to test the performance of an extreme approach with floating basis functions. Near-Hartree-Fock energies and structures are obtained by optimizing the positions of the nuclei and of nearly all basis functions independently with relatively small basis sets ofs- type functions only. Advantages and disadvantages of this approach are discussed.     

An experimental study to swing up and control a pendulum with two reaction wheels

Meccanica - An experimental study is discussed on a strategy that combines on-off and sliding mode control to swing up and control a pendulum with two reaction wheels in the upright position. The...     

Gram scale synthesis of 3-fluoro-1-hydroxyacetone phosphate: a novel donor substrate in rabbit muscle aldolase-catalyzed aldol reactions

An efficient gram scale synthesis of 3-fluoro-1-hydroxyacetone phosphate (FHAP) has been developed. As a close analog to dihydroxyacetone phosphate, FHAP was used as a novel donor substrate for rabbit muscle aldolase catalyzed reactions. The different binding affinities of the gem-diol and keto form of FHAP were studied by (19)F-NMR.