JTW's Evolutionary Origins - Author: Wachtershauser, Gunter

The Problem of Pathway Reconstruction

"The most difficult problem of biochemical phylogeny is concerned with the elucidation of patterns of evolutionary changes, E5 to E11. They frequently change not only the catalyst of a pathway, but also the very constitution of the pathway itself. This problem can be subdivided into the diagnostic problem of identifying those extant pathways that underwent extensive evolutionary changes and the problem of reconstruction of the actual course of pathway evolution."

The Class Reaction Principle

[pp. 124]

"For the problem of reconstructing a precursor pathway, we make use of the class reaction principle, which assumes that one reaction type covers plural analogous constituents. It is based notably on the well known chemical rules of structural analogy such as:

The Principle of Competitive Reactions

[pp. 125]

"This class reaction principle means that by going backward against the direction of evolution, the reaction classes get smaller but bigger in members. It is indeed remarkable that the central metabolism is composed of a few reaction types only, while going outward into the peripheral or secondary metabolism, we meet more and more exotic reaction types due to an increasing versatility of the enzymes. Similarly we will make use of the principle of competition reactions (one constituent undergoes plural reactions)."

Reconstruction of Historic Relations

[pp. 125]

"Finally, of course, we will consider... [The] reconstruction [of] the (tentantively) accepted historic relations.

For monitoring the progress in such a programme of speculative pathway reconstruction,
we go by the increase of explanatory power.

In the course of this theory development, we will sometimes have to revise a pathway and at other times the list of historic relations or their temporal order."

• 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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