NDLI: Effects of Silicate, Phosphate, and Calcium on the Stability of Aldopentoses

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Nitta, Sakiko Furukawa, Yoshihiro Kakegawa, Takeshi
Description	Country affiliation: Japan Author Affiliation: Nitta S ( Department of Earth Sciences, Tohoku University, Sendai, Japan.); Furukawa Y ( Department of Earth Sciences, Tohoku University, Sendai, Japan. furukawa@m.tohoku.ac.jp.); Kakegawa T ( Department of Earth Sciences, Tohoku University, Sendai, Japan.)
Abstract	Ribose is an important constituent of RNA: ribose connects RNA bases and forms a strand of sugar phosphates. Accumulation of ribose on prebiotic Earth was difficult because of its low stability. Improvement in the yield of ribose by the introduction of borate or silicate in a formose-like reaction has been proposed. The effects of borates have been further analyzed and confirmed in subsequent studies. Nonetheless, the effects of silicates and phosphates remain unclear. In the present study, we incubated aldopentoses in a highly alkaline aqueous solution at a moderate temperature to determine the effects of silicate or phosphate on the degradation rates of ribose and its isomeric aldopentoses. The formation of a complex of silicate (or phosphate) with ribose was also analyzed in experiments with $^{29}Si$ and $^{31}P$ nuclear magnetic resonance (NMR). We found that silicate or phosphate complexes of ribose were not detectable under our experimental conditions. The stability of ribose and lyxose improved after addition of 40-fold molar excess (relative to a pentose) of sodium silicate or sodium phosphate to the alkaline solution. The stability was not improved further when an 80-fold molar excess of sodium silicate or sodium phosphate was added. Calcium was removed from these solutions by precipitation of calcium salts. The drop in $Ca^{2+}$ concentration might have improved the stability of ribose and lyxose, which are susceptible to aldol addition. The improvement of ribose stability by the removal of $Ca^{2+}$ and by addition of silicate or phosphate was far smaller than the improvement by borate. Furthermore, all aldopentoses showed similar stability in silicate- and phosphate-containing solutions. These results clearly show that selective stabilization of ribose by borate cannot be replaced by the effects of silicate or phosphate; this finding points to the importance of borate in prebiotic RNA formation.
File Format	HTM / HTML
ISSN	01696149
Issue Number	2-3
Volume Number	46
e-ISSN	15730875
Journal	Origins of Life and Evolution of Biospheres
Language	English
Publisher	Springer
Publisher Date	2016-06-01
Publisher Place	Netherlands
Access Restriction	Subscribed
Subject Keyword	Discipline Molecular Biology Discipline Biology Calcium Chemistry Origin Of Life Pentoses Phosphates Ribose Silicates Alkalies Borates Carbohydrates Evolution, Chemical Hydrogen-ion Concentration Models, Chemical Rna Water Journal Article Research Support, Non-u.s. Gov't
Content Type	Text
Resource Type	Article
Subject	Medicine Ecology, Evolution, Behavior and Systematics Space and Planetary Science

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