Last Results In Contemporary Protein Molecules Crystallography

Submitted by: Joleytor

Protein crystallography plays one of the most important role in the structural study of the different biological molecules. Currently in is impossible to analyse enzyme functionality without knowing the exact molecular structure. The detailed information about positions of all amino acid residues is crucially important for analysis of mechanisms of enzyme activity.

The protein crystallography is relatively new branch of science, which was started from studies of the DNA-double helix structure by and Francis Crick and James Watson in April 1953. Currently, it is possible to solve the structure of whole virus with high definition by this technique.

From 1953 the biomolecular crystallography made great breakthrough. It was possible only due to the development of computing power of modern computers. The computational requirements of protein crystallography are very large. For example, the structure of leucine dehydrogenase contains eight polypeptide chains, each of them contains few hundreds amino acids, and each of them contains about 15 atoms, which is in total about 40,000 atoms. For each atom we can calculate three positional and almost ten temperature factors. As a result, we need define 4*40,000 = 160,000 parameters. For larger molecules the number of such variables can go up to about half-million. Minimization of equation with such amount of independent parameters is not very simple task. Data collection is difficult as well. Modern X-Ray detectors produce about 30 Mb of raw data per few second. The storage of such informational flow is another problem for computer techniques. Luckily, last few years these computational problems were solved.

Modern enzyme structures, solved by protein crystallography allow to identify not only the exact position of each atoms, including the position of hydrogen atoms but also detect the structural changes related with the enzymatic reactions. This will allow to investigate in great details many of the enzymatic reactions, which was previously only predicted on the basis of the catalytic amino acid residues involved into reaction and on the basis of the static picture of atoms. These data will be very useful in biotechnology. The most important is the drug design which is impossible without the exact knowledge of catalytic act.

Despite the great progress in biomolecule structural studies, there are lot of scientific problems which was not solved yet. Despite the exact knowledge about structures of many thousand enzymes, we do not understand the principles of proteins organization and it is almost impossible to predict enzyme 3D structure. The other problem is to understand the evolution of enzymes. Currently we know the static picture of protein structures, but how they were developed during evolution? At the moment only small ideas and examples of protein evolution are known. Another great white area in our knowledge is the protein crystallization. We can produce almost any protein in bacterial cells. Protein purification is a quite routine procedure with the standard set of technological steps, but the final step, the protein crystallization is a matter of luck, rather than science. The only one technique can get the results - many trials of different crystallization conditions.

As a conclusion it is possible to note, that despite that X-Ray crystallography is more than 50 year old, this scientific area still have a lot of unknown bits and it is very interesting and perspective scientific area for young biologist, chemist and physicist.

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Read more about crystallography of proteins on the author web site. For your knowledges you also can read about short protein - peptides written by author.

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