Accumulation of ribose in borate-rich prebiotic environments

Abstract

Ribose is a sugar that constitutes RNA and thus is an essential molecule for the origin of life. Ribose is known to be formed by the formose reaction, a condensation reaction of formaldehyde, but the environment in which ribose accumulates is unclear. Borate stabilizes ribose, and it also inhibits ribose formation. In this study, we investigate the effects of borate on the formose-type reaction by quantifying the transitions of various sugar amounts produced by the response. Ribose was quickly formed and reduced its amounts in all the reactions. The higher the concentration of borate, the lower the maximum concentration of ribose. However, the rate of ribose decrease was substantially declined by the effect of borate, resulting in the amount of remaining ribose in a borate-rich experiment being more than ten times higher than that in a borate-free experiment after 72 hrs. These results suggest that borate is effective in facilitating the accumulation of ribose over geological time scales on early Earth.