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Table 2 Enzyme numbers and cofactor equivalents for isobutyraldehyde production from C1 feedstocks

From: Toward bioproduction of oxo chemicals from C1 feedstocks using isobutyraldehyde as an example

Substrate

C1-Pathway

Intermediate

Enzyme number

ATP cost

NAD(P)H equivalents

Refs.

CO2

WLP

acetyl-CoA

12

2

11

[47]

CO2

rGlyP

pyruvate

11

4

11

[42, 48]

CO2

rTCA cycle

acetyl-CoA

13

4

11

[49, 50]

CO2

HCO3−

DC/HB cycle

acetyl-CoA

18

6

11

[51]

CO2 HCO3−

HP/HB cycle

acetyl-CoA

20

8

11

[52, 53]

HCO3−

3-HP bicycle

pyruvate

22

10

11

[54, 55]

CO2

CBB cycle

GAP

21a

14a

11a

[56]

CO2

ASAP

pyruvate

13a

− 2a

11a

[13]

  1. All calculations are based on converting CO2 equivalents to isobutyraldehyde via pyruvate. NAD(P)H equivalents refer to the reducing power generated from NADH, NADPH, ferredoxin, H2, or H2O.
  2. WLP: Wood–Ljungdahl pathway, rGlyP: reductive glycine pathway, rTCA cycle: reductive TCA cycle, DC/HB cycle: dicarboxylate/4-hydroxybutyrate cycle, HP/HB cycle: 3-hydroxypropionate/4-hydroxybutyrate cycle, 3-HP bicycle: 3-hydroxypropionate bicycle, CBB cycle: Calvin–Benson–Bassham cycle, ASAP: artificial starch anabolic pathway.
  3. aHere, we assume that the CBB cycle and ASAP are employed to convert CO2 to glyceraldehyde-3-phosphate (GAP), then a few steps of the glycolysis pathway are utilized to convert GAP to pyruvate, which will be further used to produce isobutyraldehyde