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Live Molecules Crystallography News
Large Molecules crystallography plays one of the most important role in the structural study of the different enzymes. Currently in is impossible to analyse enzyme functionality without knowing the exact molecular structure. The detailed information about positions of all atoms is crucially important for analysis of mechanisms of enzyme activity.
The protein crystallography is relatively young branch of science, which was started from studies of the DNA-double helix structure by and F. Crick and James Watson in April 1953. Currently, it is possible to solve the structure of whole virus with atomic resolution by this technique.
From first experiments of and F. Crick and J. Watson the protein 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 350 amino acids, and each of them contains about 15 atoms. So, finally we have got about 40 thousand 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 millions. 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 biological molecule 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 molecular motion. 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 these amino acid residues. These data will be very useful in medicine, biotechnology and other field of human life. The most important is the drug design which is impossible without the exact knowledge of enzymatic 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 more than ten thousand proteins, we do not know the principles of proteins organization and it is almost impossible to predict enzyme three dimensional structure. The other problem is to understand the evolution of biological molecules. Currently we know the modern picture of protein structures, but how they were developed during time? At the moment only few theories of protein evolution are known. Another great white area in our knowledge is how enzymes are crystallized. We can produce almost any enzyme by genetic techniques. Protein purification is a quite routine procedure with the standard set of procedures, 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.
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