Autocatalytic reaction cycles for non-enzymatic synthesis of life-sustaining sugars in neutral media

Abstract

Biological assimilation of CO2 to produce sugars occurs in metabolic cycles with an autocatalytic nature, such as the Calvin cycle and reverse citric acid cycle. The formose reaction, in which sugars are non-enzymatically synthesized from formaldehyde under basic conditions, involves such an autocatalytic cycle and has attracted much interest from the viewpoint of the abiotic chemical synthesis of sugars. However, many side reactions are indiscriminately accelerated by hydroxide ions, which results in a very low selectivity of sugar formation. Here we report non-enzymatic sugar synthesis under neutral conditions using mono-oxometalate as a catalyst to form an autocatalytic cycle. The construction of an autocatalytic reaction system under neutral conditions significantly improved the selectivity of sugar formation. It was also demonstrated that abiotically synthesized sugars could sustain the growth of microbial cells.