JTW's Evolutionary Origins - Author: Wachtershauser, Gunter
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Reactions Involved in the Chemoautotrophic Metabolism

Rxn b:
Carboxylation

[pp. 127-128]


Example #1b

[From: RCC pathway - Fig.5]

As written:

Pyruvate (Py) --b--> Oxaloacetate (OA)

COOH-C(SH)=CH2 --b--> COOH-CH=C(SH)-COOH

Breakdown:

Pyruvate (Py) <==H2S==> Thioenolpyruvate (TPy)

COOH-CO-CH3 <==H2S==> COOH-C(SH)=CH2

Thioenolpyruvate (TPy) --b-->

COOH-C(SH)=CH2 --b--> COOH-CH=C(SH)-COOH

<==H2S==> Oxaloacetate (OA)

COOH-CH=C(SH)-COOH <==H2S==> COOH-CH2-CO-COOH

note:

Pyruvate in the presence of H2S is in equilibrium with it's thioenol-form.

Example #2b

[From: RCC pathway - Fig.5]

As written:

2-Ketoglutarate (KG) --b--> Oxalosuccinate (OS)

COOH-CH2-CH=C(SH)-COOH --b--> COOH-CH2-C(COOH)=C(SH)-COOH

Breakdown:

2-Ketoglutarate (KG) <==H2S==>

COOH-CH2-CH2-CO-COOH <==H2S==> COOH-CH2-CH=C(SH)-COOH

--b-->

COOH-CH2-CH=C(SH)-COOH --b--> COOH-CH2-C(COOH)=C(SH)-COOH

<==H2S==> Oxalosuccinate (OS)

COOH-CH2-C(COOH)=C(SH)-COOH <==H2S==> COOH-CH2-CH(COOH)-CO-COOH

note:

2-Ketoglutarate in the presence of H2S is in equilibrium with it's thioenol-form
  • 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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