JTW's Evolutionary Origins - Author: Wachtershauser, Gunter
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The Evolution of the Sugar Pathways in a Chemoautotrophic Metabolism
"Phosphorylated trioses are similarly unstable as long as they are in aqueous solution. If they are, however, bonded to a mineral with positive surface charges such as pyrite, the phosphotrioses are expected to form intermolecular hemiacetal bonds, which may be considered quasi-intramolecular. The resulting dimeric or oligomeric structures are chemically stable due to a blocking of the carbonyl groups and due to polyanionic surface bonding. For their analogy with ribose these hypothetical structures are called 'phosphotribose'. This explains how phosphotrioses, in spite of their instability in solution, came to play a pivotal role in the metabolism and it explains why the sugar metabolism uses almost exclusively phosphorylated sugars. This explanation is a unique feature of the theory of surface metabolism: the earliest function of phosphate esters is the function of surface bonding (Wachtershauser, 1988d). Previously, the function of organic phosphates was seen strictly in terms of chemical reactivity (Westheimer, 1987) and the prevention of leakage out of the cell (Davis, 1958)."
[Wachtershauser, 1992, pp. 98-99]
"The thermodynamic stability of C-S bonds, in conjuction with the high reactivity of thio or mercapto groups, has important consequences for a number of pathway evolutions, notably for the the origin of the phosphorylated sugar pathways, which are retrodicted by HR10 into thiosugar pathways."
[Wachtershauser, 1992, pp. 133]
"...the theory of a pyrite pulled surface metabolism suggests that the first function of phosphate esters was that of surface bonding to a cationic mineral surface (Wachtershauser 1988d) With phosphate groups as surface-bonding mediators, the surface metabolism can include constituents (e.g. sugars, glycerol lipids, serine) which by themselves are not surface bonders."
[Wachtershauser, 1992, pp. 136]
- Wachtershauser, Gunter
- Groundworks for an Evolutionary Biochemistry: The Iron-Sulphur World
- Progress in Biophysics and Molecular Biology: Vol. 58, No. 2, pp.85-202
- 1992
- [Pubmed]
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