November 2, 2011 16:42
Chinese biologists turn ordinary rice seed protein "factory" that produces albumin — the main protein component of human blood, have developed a technology of extracting protein from this "bioreactor" and published their findings in an article in the journal Proceedings of the National Academy of Sciences.
Albumin — is the main blood protein produced in the human liver. It has the transport properties, delivering to the organs and tissues of fatty acids and some medications. At the moment, albumin, which is used for medical purposes is extracted from donated blood. As they note, the patient can get along with the serum, all viruses that are hidden in it, including Hepatitis B and HIV, which often happened in practice.
A team led by Ian Daychana (Daichang Yang) of the State Laboratory of transgenic rice in Wuhan (China), inserted into the genome of ordinary rice several human genes that are "learned" to collect this plant albumin in the "industrial" scale.
Other groups have previously tried to "educate" the production of albumin, other plants, microorganisms and animals, but all their attempts to come across an extremely low amount of albumin produced by their wards. For example, transgenic potato tubers and tobacco leaves contain about 0.02% albumin. Recently, biologists have been able to achieve efficiency of 11% for tobacco leaves, but even such a "performance" green factory was not enough from the commercial point of view.
In contrast, the "bioreactor" Ian and his team, dubbed as a new variety of rice scientists themselves, can produce large amounts of protein, which can be easily extracted from the grains of rice.
The scientists modified the conventional seed rice genome (Oryza sativa) in such a way that the plant was massing albumin molecules in protein vacuoles — intracellular "vaults" — in maturing seeds.
Biologists have prepared a number of special strains of bacteria of the genus Agrobacterium, which in nature to cause cancer in plants and feed on waste products of tumor cells. Scientists extracted from bacteria cancer plasmids — circular piece of DNA bacteria — and replaced it with "stuffing" for several human genes required for albumin "pipeline."
They then planted the culture of these bacteria on the roots of plants and several adults, nine strains of transgenic rice. According to scientists, these "bioreactors" contain from 1.4% to 10.6% of the cells with genes albumin, most of which is concentrated in the grains of rice. Scientists raised several subsequent generations of "protein" rice and found that a new variety of rice is stable with a genetic point of view.
After that biologists have identified himself albumin from seeds of the rice, and compared it with the human protein. Molecular weight, amino acid sequence, three-dimensional structure and the decomposition temperature of the "plant" and human albumin were identical.
Scientists have added a small amount of protein solutions fatty myristic acid — a major component of animal fats — and observe the behavior of albumin. Human and "plant" proteins behaved in exactly the same — they are an equal number of molecules attached to the same points. Other molecules, including anticoagulant warfarin and analgesic naproxen are equally effective in binding with proteins.
After that biologists tested the rice albumin rat population with cirrhosis of the liver. Albumin is synthesized in the liver and serious violations in the work lead to a reduction in the number of animals in the blood, which leads to a number of serious disorders — an animal loses weight and has the metabolism. Scientists are routinely given a small dose of albumin in the blood of rats, which improved their health and restore normal metabolism.
After ensuring the safety and effectiveness of a bioreactor, the researchers developed a technique for extracting the protein, it is cheap enough for the masses. The production cycle is 48 hours and includes three stages — crushing seeds, urinary protein and its purification. According to preliminary estimates, this technology can remove up to 50% protein from grains, which corresponds to 2.75 g of albumin per kilogram of ripe rice. The extracted protein in their purity is not inferior to "normal" serum albumin.
Yang and his colleagues believe that their technology would eliminate other sources of albumin after checking on the human cells and the preparation of special fields that are isolated from the outside world.