JTW's Evolutionary Origins - Author: Wachtershauser, Gunter

Rxn c: Reductive Desulphuration

Postulate 3

[pp. 128-129]

-C-SH + FeS --^c--> -C-H + FeS₂

General Reaction Class:

HS-C=X (X = =O, =S, =N-, =C );

HS-C-Y (Y = -H, -S-, -O-, -N )

---

Example #1c

[From: RCC pathway - Fig.5]

As written:

Oxaloacetate (OA) --^c--> Fumarate (Fu)

COOH-CH=C(SH)-COOH --^c--> COOH-CH=CH-COOH

Breakdown:

Oxaloacetate (OA) <==^H₂S==>

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

--^c--> Fumarate (Fu)

COOH-CH=C(SH)-COOH --^c--> COOH-CH=CH-COOH

note:

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

---

Example #2c

[From: RCC pathway - Fig.5]

As written:

Oxalosuccinate (OS) --^c--> Aconitate (Aco)

COOH-CH₂-C(COOH)=C(SH)-COOH --^c--> COOH-CH₂-C(COOH)=CH-COOH

Breakdown:

Oxalosuccinate (OS)

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

--^c--> Aconitate (Aco)

COOH-CH₂-C(COOH)=C(SH)-COOH --^c--> COOH-CH₂-C(COOH)=CH-COOH

note:

Oxalosuccinate in the presence of H₂S is in

equilibrium with it's thioenol-form

---

Example #3c

[From: RCC pathway - Fig.5]
&
[From: (OA) to (Su) Pathway - Fig.6]

As written:

Thiomalate (TM) --^c--> Succinate (Su)

COOH-CH₂-CH(SH)-COOH --^c--> COOH-CH₂-CH₂-COOH

Breakdown:

---

Example #4c

[From: (KG) to Glutarate Pathway - Fig.7]

As written:

2-Dimercaptoglutarate (DMG) --^c--> 2-Mercaptoglutarate

COOH-C(SH)₂-CH₂-CH₂-COOH --^c--> COOH-CH(SH)-CH₂-CH₂-COOH

Breakdown:

---

Example #5c

[From: (KG) to Glutarate Pathway - Fig.7]

As written:

2-Mercaptoglutarate --^c--> Glutarate

COOH-CH(SH)-CH₂-CH₂-COOH --^c--> COOH-CH₂-CH₂-CH₂-COOH

Breakdown:

---

Example #6c

[From: (KG) to Glutarate Pathway - Fig.7]

As written:

--^c--> Glutaconate (Gl)

COOH-C(SH)=CH-CH₂-COOH --^c--> COOH-CH=CH-CH₂-COOH

Breakdown:

---

Example #7c

[From: (KG) to Glutarate Pathway - Fig.7]

As written:

--^c--> 2-Hydroxy-glutarate (HG)

COOH-C(OH)(SH)-CH₂-CH₂-COOH --^c--> COOH-CH(OH)-CH₂-CH₂-COOH

Breakdown:

• 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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