Ribose Selected as Precursor to Life

Abstract

The chemical or prebiotic evolution referred also to as pre-Darwinian evolution describes chemical reactions up to the origin of a self-replicating system that was capable of Darwinian evolution. These chemical processes took place on Earth between about 3.7 and 4.5 billion years ago when cellular life came into being. The pre-Darwinian chemical evolution usually assumes hereditary elements, but does not regard them as self-organizing processes. Physical and chemical self-organization led to uninterrupted pre-Darwinian and Darwinian evolution. Thus, it is not justified to distinguish between different types of evolution. From the many possible solutions, evolution selected among those reactions that generated catalytic networks incorporating chemical sequence information and under gradually changing circumstances produced a reproducible and stable living system that adapted to these conditions. Major issues in this review involve prebiotic reactions leading to genetic evolution involving (1) abiotic sources of components of ribonucleotides and xenobiotic nucleotides, (2) formation of prebiotic RNA, (3) development of genetic RNA from random-sequence noncoding RNA, (4) transition from RNA World to DNA Empire, (5) the role of oxygenic photosynthesis in genetic transitions, and (6) hierarchical arrangement of processes involved in the optimized genetic system.

C-Ribosylating Enzymes in the (Bio)Synthesis of C-Nucleosides and C-Glycosylated Natural Products

“…In cases where the corresponding αanomer was synthesized chemically, the C-α-riboside typically exhibited low biological activity. 45 Various C-nucleosides have been discovered from the phylum Actinobacteria 7 (Figure 1) and are well known for the antimicrobial and antiviral activity 13 they exhibit: showdomycin 15,46−49 (3), oxazinomycin 50−53 (4), alnumycin 54−57 (5), malayamycin 58,59 (6), pseudouridinemycin 60−63 (7), pyrazofurin 64−67 (8), and formycin 64,68 (9a, 9b). Besides pharmaceutically active molecules, bacteria produce the highly water-soluble blue pigment indochrome (10) that has potential applications as a technical colorant in foods and other sectors of industry.…”

“…The pentose d -ribose is the main sugar building block of a large class of nucleosides and phosphorylated derivatives thereof (nucleotides). − Ribonucleotides are the precursors of RNA and play a central role in cellular energy and redox metabolism. ,, They are key molecules of various branches of natural biosynthesis. − The common nucleoside core structure has a β- d -ribofuranosyl unit attached to a nitrogen of the nucleobase aglycone. − In certain nucleosides, though, the canonical N -β-ribosyl pattern is replaced by a naturally rare C -β-ribosyl feature, as shown in Figure (e.g., 1a, 2a ). The chemical consequences of β-ribosyl attached to the aglycone by a carbon–carbon instead of carbon–nitrogen bond are of great biological interest. − …”

Carbamoyl phosphate and its substitutes for the uracil synthesis in origins of life scenarios

“…1). The sugar moiety, D-ribose issued from phosphoribosyl pyrophosphate (PRPP) is then incorporated to the structure [15]. The pyrimidine ring atoms come from L-aspartic acid (L-Asp) and carbamoyl phosphate (CP).…”

Carbamoyl phosphate and its substitutes for the uracil synthesis in origins of life scenarios

“…1). The sugar moiety, D-ribose issued from phosphoribosyl pyrophosphate (PRPP) is then incorporated to the structure 15 .…”