AG Fritz

Protein Purification and Sequencing

The purification of proteins is a fundamental step prior to almost every experiment in our lab. A major part of the research of biologists in our lab is the identification and sequencing of proteins from nacre of Haliotis laevigata. From the protein mixture extractable from nacre different proteins have to be isolated for further studies.

Currently different chromatography systems are used for this task. Our lab is equipped with a high pressure liquid chromatography system, an ion exchange chromatography system and gel chromatography columns for protein purification and separation.

An UV-VIS spectrophotometer and a luminescence spectromenter can be used for further analysis of the proteins. Additionally microcrystal binding experiments are conducted to reveal the function of proteins from nacre.

Author: Malte Launspach

AG Fritz

Atomic force microscopy

Our group has many years of scientific experience with the atomic force microscope (AFM). Briefly, this technique uses a   - often pyramidal - tip mounted on a cantilever. The apex of this (pyramidal) tip has a diameter in the nanometer range and is moved lateral over a surface. The surface topography (in contact mode) causes a deflection of the cantilever which is processed into a height signal. The appealing characteristic of this technique is the possibility to image the effects of proteins in an aqueous environment. In our lab the AFM is commonly used to image the effect of proteins or peptides on calcium carbonate (calcite or aragonite) surfaces. The institute is equipped with an Asylum MFP3D, a Nanosope IIIa and a home-build AFM.

We currently are establishing the AFM force spectroscopy method. The aim is to measure the interaction energy between proteins/peptides and mineral surfaces as well as polysaccharide surfaces.


Molecular dynamic simulations / Protein Modeling

Once the structure of a nacre protein is known we investigate the interaction of this protein with mineral surfaces and polysaccharides in silico. As an additional technique a molecular dynamic simulation can provide insight into interaction mechanisms.

If the protein stucture is not known but the protein sequence we use the homology modeling method to get a preliminary structure of the protein which can give hints of the protein function.

Author: Malte Launspach

Scanning electron microscopy / Transmission electron microscopy

A cooperation with the institute of solid state physics facilitates the use of a scanning electron microscope (SEM: Nova 200, FEI Eindhoven, the Netherlands) and of a transmission electron microscope (TEM: FEI, TITAN 80/300, Eindhoven, the Netherlands) to investigate our specimens. With the SEM the surface of a specimen is imaged. thus this method is mainly used to investigate the morphology of samples, in our case of small calcium carbonate (CaCO3) crystals with diameters under 10μm. The resolution in the SEM is in the range of 10nm. The TEM reveals a much higher resolution of up to 0.08nm and is therefore an adequate method to analyze the crystallographic structure of the aragonite (a CaCO3 polymorph) platelets of nacre as well as of in vitro grown CaCO3 crystals. Additionally electron diffraction provides information on the crystallographic structure. The used TITAN is equipped with detectors to record energy dispersive x-ray (EDX) spectra and electron energy loss spectra (EELS) to determine the elements in the sample. Additionally electron tomography can be performed to create three dimensional models of certain specimen features. Not just crystalline specimens but also biological specimens like tissues can be investigated using TEM, but these samples require very special preparation procedures.

Author: Katharina Gries

Home-build devices

If standard equipment is not suitable for our purposes or special equipment is needed we build it. Currently our lab is equipped with a contact angle measuring device and a patented double-diffusion chamber for ... .