Analysis of the proteins possessed by the last common ancestor and the organisms present before it

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We have resurrected the gene of the nucleotidediphosphate kinase (NDK) possessed by the common ancestor of Bacteria and Archaea, and analyzed the thermal stability of the protein produced from the resurrected genes. The ancestral NDKs showed stability close to 110 degree C, suggesting the common ancestors of Bacteria and Archaea were thriving at the temperature between 80 and 100 degree C. The NDK of the last common ancestor, commonote, was also resurrected and reproduced. The ancestral NDK showed the high stability, suggesting that the commonote were living at 75 degree C or higher temperature. The ancestral NDKs from which one of the 20 amino acid species were removed, were produced and whose stability and activity were analyzed. The results showed the amino acid species that is not absolutely required for the stability and activity.