Proteins with selenocysteine
Researchers from the University of Texas have demonstrated a way to increase the stability of proteins used as drugs. This will increase the efficiency and ease of use of medicines, reduce the dose and frequency of their administration and lead to rationalization of healthcare costs.
Many protein preparations, including insulin, growth hormone, interferon and monoclonal antibodies, have a short active life cycle in the human body. These drugs are proteins – sequences of amino acids. One of them, cysteine, forms weak disulfide bonds. In the presence of certain compounds found in human cells and blood, they easily disintegrate, and the active substance of the drug is rapidly destroyed.
Scientists have proposed replacing cysteine with another amino acid – selenocysteine, which forms stronger diselenide bonds. According to the results of the study, this change will lead to the creation of medicines that have the same effects, but they are more stable and can last longer in the body.
Genetically modified bacteria are used as factories for the production of therapeutic proteins. But they have some limitations that previously prevented the use of selenocysteine. Thanks to a combination of genetic engineering and directed evolution, researchers were able to reprogram the biology of bacteria.
Researchers have changed the genetic code of E.coli bacterial strains, removing all restrictions on the replacement of cysteine with selenocysteine. Modified strains retain the edited genetic code indefinitely.
The method was described by scientists led by Ross Thyer back in 2015, now they have demonstrated its practical application by creating appropriate therapeutic proteins – including the functional area of the drug trastuzumab (Herceptin) for the treatment of breast cancer. They showed that new proteins last longer in conditions similar to the human body, compared with "classic" proteins containing cysteine.
The authors filed a patent application for the technology of synthesis of stable proteins and peptides with selenocysteine described in the article, the patent was licensed.
Article by R. Thyer et al. Custom selenoprotein production enabled by laboratory evolution of recoded bacterial strains is published in the journal Nature Biotechnology.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru Based on UT News: A Change in Bacteria's Genetic Code Holds Promise of Longer-Lasting Drugs.