Humboldt State University ® Department of Chemistry

Richard A. Paselk

Chemistry 438 - Spring 2011

BIOCHEMISTRY REVIEW

Week 12

Carbohydrate Metabolism

Give a pathway for the breakdown of glycerol to acetyCoA, naming enzyme types and energy steps.

Answer:

  • glycerol glycerol-P (Kinase) -1 ATP
  • glycerol-P DHAP (DH) 1 NADH
  • DHAP Ga-3-P
  • Ga-3P 1,3-bisPGA (DH) 1 NADH
  • 1,3-bisPGA 3-PGA (Kinase) 1 ATP
  • 3-PGA 2-PGA PEP
  • PEP Pyruvate (Kinase) 1 ATP
  • Pyruvate acetylCoA (DH Complex) 1 NADH

Give pathways for the breakdown of Fructose, Mannose, and Galactose to acetyCoA, naming enzyme types and energy steps.

What are the main entrance/exit points of carbohydrate metabolism?

Answer:

  • glycogen enters/exits at G-6-P
  • glycerol enters/exits at DHAP (see above)
  • Pentose P Shunt (also R-5-P)
    • exits at G-6-P
    • enters/exits (for transformation rxns) at F-6-P and Ga-3-P
  • Kreb's TCA Cycle intermediates
    • catabolism
      • enter with acetylCoA adding to oxalacetate
    • anapleurosis
      • enters at PEP via oxalacetate/malate
      • exits at Pyruvate via oxalacetate/malate
  • Fructose (human liver) enters/exits at DHAP via F-1-P
  • Galactose enters/exits at G-6-P

Kreb's TCA Cycle

Review aerobic pathway energy generation:

 Reaction
Energy Product

factor
ATP Equivalents
(@2.5 ATP/NADH)
ATP Equivalents
(@3 ATP/NADH)
Hexokinase ADP 1 -1 -1
PFK  ADP 1 -1 -1
Ga-3-P DH NADH 2 5 6
PGA Kinase ATP 2 2 2
Pyruvate Kinase ATP 2 2 2
Pyruvate DH Complex

 NADH

 2

5
6
Isocitrate DH NADH

2

5
6
2-oxoglutarate DH Complex NADH

2

5
6
Succinyl-CoA Synthetase GTP

2

2
2
Succinate DH FADH2

2

3
4
Malate DH NADH

2

5
6

  TOTAL=

32
38

 Reaction
Energy Product

factor
ATP Equivalents
(@2.5 ATP/NADH)
Pyruvate DH Complex NADH

1

2.5
Isocitrate DH NADH

1

2.5
2-oxoglutarate DH Complex NADH

1

2.5
Succinyl-CoA Synthetase GTP

1

1
Succinate DH FADH2

1

1.5
Malate DH NADH

1

2.5

  TOTAL=

12.5

* Note that the energy yield in this step is shuttle and thus tissue dependent. For tissues using the glycerol-P shuttle get 1.5, whereas for tissues using the malate-aspartate shuttle get 2.5.

 Reaction
Energy Product

factor
ATP Equivalents
(@2.5 ATP/NADH)
Lactate DHcytosol (Lac  Pyr) NADH

1

(1.5) 2.5*
Pyruvate DH Complex

 NADH

 1

 2.5
Isocitrate DH NADH

1

2.5
2-oxoglutarate DH Complex NADH

1

2.5
Succinyl-CoA Synthetase GTP

1

1
Succinate DH FADH2

1

1.5
Malate DH NADH

1

2.5

  TOTAL=

(13.5) 15

 Reaction
Energy Product

factor
ATP Equivalents
(@2.5 ATP/NADH)
2-oxoglutarate DH Complex NADH 1 2.5
Succinyl-CoA Synthetase GTP 1 1
Succinate DH FADH2 1 1.5
Malate DHcytosol NADH 1 2.5
PEP Carboxykinase GDP 1 -1
Pyruvate kinase ATP 1 1
Pyruvate DH Complex NADH 1 2.5
Isocitrate DH NADH 1 2.5
2-oxoglutatrate DH Complex NADH 1 2.5
Succinyl-CoA Synthetase GTP 1 1
Succinate DH  FADH2 1 1.5
Malate DH NADH 1 2.5

  TOTAL =

20

 Reaction
Energy Product

factor
ATP Equivalents
(@2.5 ATP/NADH)
Malate DHmitosol(oxal mal) NAD+ 1 -2.5
Malate DHcytosol NADH 1 2.5
PEP Carboxykinase GDP 1 -1
Pyruvate kinase ATP 1 1
Pyruvate DH Complex NADH 1 2.5
Isocitrate DH NADH 1 2.5
2-oxoglutatrate DH Complex NADH 1 2.5
Succinyl-CoA Synthetase GTP 1 1
Succinate DH  FADH2 1 1.5
Malate DH NADH 1 2.5

  TOTAL=

17.5

Glycogen Metabolism

Pentose Phosphate Shunt (aka Hexose Monophosphate Shunt)

Schedule

 

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©R A Paselk

Last modified 1 April 2011