Biomedical subjects

Robert Zeidler

Publications and source records attributed to Robert Zeidler.

4 recordsLinked to original sources

PubMed2005

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.

Adsorption↗

PubMed2005

Concentration and desalting of peptide and protein samples with a newly developed C18 membrane in a microspin column format.

Protein identification plays an important role in today's academic and industrial proteomic research. Commonly used methods for the separation of proteins from complex samples include liquid chromatography (e.g., ion exchange, reversed-phase, hydrophobic interaction), or types of gel electrophoresis (e.g., 1d and 2d PAGE). Relevant proteins separated in the latter way are often cut out, cleaved with trypsin "in gel," and the resulting peptide mixtures combined with matrix and spotted onto a target plate for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF-ms) analysis. Subsequently, proteins can be identified by comparison of the resulting peptide mass fingerprints against different databases.(1) since the success of protein identification can be enhanced by the desalting and concentration of the samples, an innovative C18-membrane was incorporated into a microspin column (Vivapure C18 micro spin column, Vivascience AG, Hannover, Germany) to analyze its performance for sample preparation prior to MALDI-ToF-ms. Rapid concentration of single or multiple 200-microl volumes through an available membrane only 2 mm in diameter allowed for analysis of very dilute samples. We observed the successful and rapid desalting of urea-containing protein samples at 100 fmol/mul up to a mass of approximately 70 KDA and the concentration of digest peptides from a solution of 1 fmol/microl using C18-membrane technology.

Animals↗

PubMed2004

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.

Centrifugation↗

PubMedDate not supplied

Innovative modular membrane adsorber system for high-throughput downstream screening for protein purification.

To develop the most efficient strategy for the purification of proteins, two types of adsorber membrane devices with different functionalities were designed and tested: 8-strips and single spin columns. The most suitable type of membrane adsorber and the optimal chromatographic loading/elution conditions for several target proteins from different biological matrices could be determined simultaneously in microliter scale. Ion exchange (IEX), metal chelate (MC), and Concanavalin A (Con A) modified membrane types were tested in the devices. Bovine serum albumin (BSA) and lysozyme were used as model proteins for investigations of the binding capacity and protein recovery percentage of the 8-strip anion exchange and the cation exchange membrane. The isolation of His(6)-tagged proteins, Bgl-His and GFP-His from fermentation broth and lysate, respectively, was performed using an 8-strip metal chelate affinity membrane loaded with different metal ions. Separation behavior of a ternary protein mixture (BSA, lysozyme, and Bgl-His) was studied in 8-strips IEX and metal chelate membrane chromatography. The Con A affinity devices were developed on the basis of metal chelate membrane spin columns loaded with Cu(2+) ions and investigated using glucose oxidase (GOD) as model protein. In summary, the advantages of the membrane adsorber technology, such as fast processing and easy scale-up, were utilized. The devices made it possible to load the membrane directly with preclarified fermentation broth or cell lysate and separate the protein of interest often in a single step.

Adsorption↗