Biology as Poetry: Bioenergetics

Bacteriophage Ecology Group

Glycolysis (stoichiometry)

C6H12O6 + 2ATP + 4ADP + 2Pi + 2NAD+ → 2C3H2O3 + 4ATP + 2ADP + NADH

Glycolysis traditionally is represented as starting with one molecule of glucose (i.e.,C6H12O6) and ending with two molecules of pyruvate (shown above instead as pyruvic acid). In addition, a total four ATP are generated, though this represents a net gain of only two ATP since two ATP are employed to "prime" the pathway, that is, are used prior the generation of a gross total of four ATPs (all as shown).

The sugar-splitting step is not explicitly shown but comes just prior to the conversion of NAD+ to NADH and also prior to the gain of four ATP. Water molecules involved in the pathway are not shown.

The enzymes involved, in order, are

     (1) Hexokinase (first ATP-priming step)
     (2) Phosphoglucose isomerase
     (3) Phosphofructose kinase (second ATP-priming step)
     (4) Aldolase (sugar-splitting step)
     (5) Triphosphate isomerase
     (6) Glyceraldehyde phosphate dehydrogenase (NAD+ → NADH step)
     (7) Phosphoglycerase kinase (generation of two ATP per starting glucose)
     (8) Phosphoglycerase mutase
     (9) Enolase
     (10) Pyruvate kinase (generation of two ATP per starting glucose)

Starting with glucose, the corresponding enzymatic products (intermediates) are

     (1) Glucose-6-phosphate
     (2) Fructose-6-phosphate (6C) + ADP
     (3) Fructose-1,6-biophosphate (6C) + ADP
     (4) Glyceraldehyde-3-phosphate (3C) + dihydroxyacetone phosphate (3C)
     (5) Glyceraldehyde-3-phosphate (3C) (from dihydroxyacetone phosphate)
     (6) 1,3 Biophosphoglycerate (3C) + NADH (two per original glucose)
     (7) 3-Biphosphoglycerate (3C) + ATP (two per original glucose)
     (8) 2-Biphosphoglycerate (3C)
     (9) Phosphoenol pyruvate (3C)
     (10) Pyruvate (3C) + ATP (two per original glucose)

The above, including structures, is basically what one commits to memory in an upper-level introduction to biochemstry class. ☺

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