Scientists from Moscow State University suggest a revolutionary approach to studying interactions of protein molecules between themselves and various surfaces. This technique is based on so-called “atomic weights”, which is a unique measuring instrument.

Combination of this device with atomic-force microscope opens unique horizons for researchers, working on cell and molecular level. Recent studies of Russian scientists were very exciting, Biologists studied how protein molecules (lysozyme) united on silicon surface and formed long and narrow bands – fibrillae. Protein type isn’t very important, however, lysozyme is quite a convenient model. An important thing is that scientists hope their new technique allows deeper understanding of processes, which cause neurodegenerative diseases, such as Alzheimer's disease. When a human being has a neurodegenerative disease, some protein molecules (amyloid-beta-peptide) in his brain behave right the same way – they aggregate into long and thin fibrillae, which later become plaques and cause brain malfunction. In order to prevent these diseases scientists need to know mechanism of this process: conditions of aggregation and forces that keep molecules together. Brand new devices could not have come at a better time.

The experiment was conducted the following way: a thin silicon plate was put into a drop of solution. Plate’s surface was either gilded or activated by oxidizers – a mixture of hydrogen peroxide and sulfuric acid. Such surface adsorbs protein molecules, forming a dense monomolecular layer with interacting forces so strong, that they can deform the silicon plate – very sensitive part of atomic weights, a so-called cantilever.

When we irradiate cantilever with laser beam and “catch” its reflection, we can detect its shift in relation to the beam, reflected from a straight plate. This shift tells us how strong surface tension of molecule layer is, as well as molecules’ adhesive power and layer’s bonding strength with the surface. The latter value is essential, since proteins are “fond of” aggregating on cell membranes’ surface rather than in “free float”. Long –term observations of the process revealed that surface tension of protein layer changed with time, which meant its structure changed too!

Atomic-force microscope helped scientists to find out what was going on inside the layer. The device showed that protein molecules, which were bonded to gilded surface, could re-form into long thin threads like spider’s web – 19 hours were enough for fibrillae to cover the surface.

There still is a long way – received results need interpretation by biochemists, gerontologists and other professionals. However, Russian scientists did the most important thing – they developed an instrumental method for obtaining quantitative data on required subject. First, quite intriguing, results in this field were reported during the conference, dedicated to various biochemical and chemical sensors.

Source:
    Russian Science News

Kizilova Anna