Ribose

Why mother Nature chose ribose as the building block for life in this planet is a fundamental question that fascinates scientists. Why not other pentoses, other sugars or even other molecules? One possibility is its formation from highly reactive formaldehyde (Formose Reaction). Nature might have favored ribose from a chaotic mix of sugars derived from formaldehyde. It’s catalyzed by basic environments, often with minerals like calcium hydroxide or metal-doped clays, which were likely present on early Earth. The Formose reaction produces a messy mix of sugars, but environmental factors, like mineral surfaces and selective binding, acted as natural sieves, favoring ribose’s emergence (see this Publication). This selective retention may have been a crucial step in the origin of RNA and eventually DNA. Furthermore, molecular modelling provided the clue that the β-D-ribose being the best fitting pentose in nucleotide building blocks of nucleic acids. And now, it has also been shown that among all the other sugars, Nature has favoured ribose as the most reactive sugar for phosphorylation (see, here).