Together with colleagues from the Institute of Biomedical Chemistry, biologists from the Research Center of Biotechnology RAS have studied a new L-asparaginase from hyperthermophilic archaea Thermococcus sibiricus. These archaea live at a depth of more than two thousand meters in a high-temperature oil reservoir in Siberia. This biotechnologically important enzyme is used in the food industry, in the development of biosensors, and in medicine due to its antitumor activity. L-asparaginase from T. sibiricus was described for the first time by the authors of this research. This enzyme differs from the previously described analogs by its increased stability and selective toxicity to cancer cells. The results were published in the International Journal of Molecular Sciences.
Newswise — L-asparaginase is an extremely important enzyme that catalyzes the conversion of the amino acid L-asparagine to L-aspartic acid and ammonia. It has been widely investigated with respect to its promising anti-cancer activity in the therapy of certain types of tumors. The application in medicine is the original and main but not the only field of use of L-asparaginase. This enzyme helps to prevent the formation of the potential carcinogen acrylamide in food products such as chips, baked goods, roasted coffee. Another field of enzyme application is the development of biosensors for monitoring of L-asparagine levels in biochemistry and food chemistry.
L-asparaginase was the first enzyme to be used in clinical practice as an anticancer agent. Some tumor cells are unable to synthesize their own L-asparagine, so they require exogenous asparagine to keep their rapid growth and proliferation. L-asparaginase exhibits a depletion effect on the concentration of L-asparagine leading to a deficiency of this amino acid and, subsequently, causes death of cancer cells.
"Despite the pronounced therapeutic effect, current commercial asparaginases have several serious drawbacks. The main ones are insufficient stability and low substrate specificity. Often, serious adverse reactions require termination of asparaginase treatment. In this view, highly stable asparaginases from microorganisms inhabiting extreme environments are considered as promising enzymes with superior performances compared to the currently used ones. These enzymes has unique properties," – says Maria Dumina, one of the authors of the study, Ph.D. in Biology, a researcher in a group of fungal genetic engineering in the Research Center of Biotechnology RAS.
Together with colleagues from the Institute of Biomedical Chemistry, scientists from the Research Center of Biotechnology RAS investigated new asparaginase from the hyperthermophilic archaea Thermococcus sibiricus, which lives at a depth of 2,350 meters in the Samotlor oil reservoir, one of the largest in Siberia. Scientists used E. coli cells for the production of recombinant protein, the properties of the purified enzyme were further studied under different conditions.
It was found that this enzyme is optimally active at 90°C – T. sibiricus lives at slightly lower temperatures – and at alkaline pH values. At the same time, it retains high activity in a wide range of temperatures and pH. It is also resistant to the presence of some metal ions and urea (can be found in biological samples).
The authors also tested the effects of the new L-asparaginase on cell lines. According to the results obtained, the enzyme inhibited the growth of different types of cancer cells, while normal cells were almost unsensitive to it.
"Our results show that this asparaginase can serve as a good alternative to currently used enzymes: it is active in a wide range of temperatures and pH, resistant to metal ions, and selectively toxic to tumors. This allows us to use it at least in biochemistry. Now we need to test asparaginase on animals – based on these future results, we will consider application of the protein in medical practice," – says Alexander Zhgun, one of the authors of the article, senior researcher, and head of the group of fungal genetic engineering in the Research Center of Biotechnology RAS.
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