Fast and efficient protein purification using membrane adsorber systems.

The purification of proteins from complex cell culture samples is an essential step in proteomic research. Traditional chromatographic methods often require several steps resulting in time consuming and costly procedures. In contrast, protein purification via membrane adsorbers offers the advantage of fast and gentle but still effective isolation. In this work, we present a new method for purification of proteins from crude cell extracts via membrane adsorber based devices. This isolation procedure utilises the membranes favourable pore structure allowing high flow rates without causing high back pressure. Therefore, shear stress to fragile structures is avoided. In addition, mass transfer takes place through convection rather than diffusion, thus allowing very rapid separation processes. Based on this membrane adsorber technology the separation of two model proteins, human serum albumin (HSA) and immungluboline G (IgG) is shown. The isolation of human growth hormone (hGH) from chinese hamster ovary (CHO) cell culture supernatant was performed using a cation exchange membrane. The isolation of the enzyme penicillin acylase from the crude Escherichia coli supernatant was achieved using an anion exchange spin column within one step at a considerable purity. In summary, the membrane adsorber devices have proven to be suitable tools for the purification of proteins from different complex cell culture samples.

Rapid prefractionation of complex protein lysates with centrifugal membrane adsorber units improves the resolving power of 2D-PAGE-based proteome analysis.

BACKGROUND: Two-dimensional gel electrophoresis (2D-PAGE) has proven over the years to be a reliable and efficient method for separation of hundreds of proteins based on charge and mass. Nevertheless, the complexity of even the simplest proteomes limits the resolving power of 2D-PAGE. This limitation can be partially alleviated by sample prefractionation using a variety of techniques. RESULTS: Here, we have used Vivapure Ion Exchange centrifugal adsorber units to rapidly prefractionate total fission yeast protein lysate based on protein charge. Three fractions were prepared by stepwise elution with increasing sodium chloride concentrations. Each of the fractions, as well as the total lysate, were analyzed by 2D-PAGE. This simple prefractionation procedure considerably increased the resolving power of 2D-PAGE. Whereas 308 spots could be detected by analysing total protein lysate, 910 spots were observed upon prefractionation. Thorough gel image analysis demonstrated that prefractionation visualizes an additional set of 458 unique fission yeast proteins not detected in whole cell lysate. CONCLUSIONS: Prefractionation with Vivapure Q spin columns proved to be a simple, fast, reproducible, and cost-effective means of increasing the resolving power of 2D-PAGE using standard laboratory equipment.

Evolutionary recruitment of a flavin-dependent monooxygenase for the detoxification of host plant-acquired pyrrolizidine alkaloids in the alkaloid-defended arctiid moth Tyria jacobaeae.

Larvae of Tyria jacobaeae feed solely upon the pyrrolizidine alkaloid-containing plant Senecio jacobaea. Ingested pyrrolizidine alkaloids (PAs), which are toxic to unspecialized insects and vertebrates, are efficiently N-oxidized in the hemolymph of T. jacobaeae by senecionine N-oxygenase (SNO), a flavin-dependent monooxygenase (FMO) with a high substrate specificity for PAs. Peptide microsequences obtained from purified T. jacobaeae SNO were used to clone the corresponding cDNA, which was expressed in active form in Escherichia coli. T. jacobaeae SNO possesses a signal peptide characteristic of extracellular proteins, and it belongs to a large family of mainly FMO-like sequences of mostly unknown function, including two predicted Drosophila melanogaster gene products. The data indicate that the gene for T. jacobaeae SNO, highly specific for toxic pyrrolizidine alkaloids, was recruited from a preexisting insect-specific FMO gene family of hitherto unknown function. The enzyme allows the larvae to feed on PA-containing plants and to accumulate predation-deterrent PAs in the hemolymph.