Living Cell Is Replaced By A Test-Tube With DNA

If living cell is replaced by a test-tube with DNA and a set of substances, it is possible to get proteins in a more simple and inexpensive way. That was done by Russian biochemists synthesizeing insulin without help of transgene Escherichia coli. The researchers’ concept was funded by the Ministry of Science and Molecular and Cellular Boioplogy, Russian Academy of Sciences.

Insulin for diabetics has been obtained so far by utilizing biotechnological synthesis. The basic material for the presious hormone – proinsulin protein – is obtained from transgene Escherichia coli, which is grown up in large quantities. However, Russian researchers have decided that it is too complicated to educe a single protein from an entire, although tiny organism, and invented a way to do without bacteria. Specialists of the Institute of Protein (Russian Academy of Sciences), Moscow State University and Institute of Bio-organic Chemistry decided to replace live bacteria by their extract and artificial reactor.

Biochemists involved a reactor of German production for proinsulin synthesis. The reacting mixture was placed in it, the mixture consisting of Escherichia coli extract, its transfer RNA, enzymes (that are in charge of manipulation with nucleic acids), amino acids and mineral salts. The matrix, from which proinsulin molecules were “printed”, was an artificially acquired plasmid – DNA molecule coding the sequence of amino acids in proinsulin.

The researchers faced challenges of a new method. Initially, a considerable part of synthesized protein precipitated in the reactor, which testifies to incorrect coagulation of a protein molecule. The researchers managed to avoid this by having changed reacting mixture volume, decreased temperature and concentration of bacterial extract. Adding detergent substances in the reactor was also helpful.

After the reaction was over, the liquid was separated from the sediment on the centrifuge, and the quantity of proinsulin was chemically determined in its fractions. To check its quality, the researchers produced insulin from proinsulin through non-complicated reactions, and then looked if it would activate human insulin receptor (this is the substance which the hormone reacts with first of all). The intensity of new insulin was compared to that of Danish company’s insulin, which had been used for a long time. It should be noted that as of today synthetic insulin proved three to four times weaker than the traditional one. However, biologists are not inclined to pessimism and they assume that this is a temporary situation. For the time being, the lack of efficiency can be made up in their opinion at the expense of high productivity – more than 1.2milligrams per milliliter of reactor. High productivity ensures low prices for new insulin, which is also of no small importance.

The idea to go in for production of synthetic proinsulin occurred with the specialists of the Institute of Protein (Russian Academy of Sciences) when they managed to get in a similar way some proteins that are generated with difficulty in bioplast.