Dihydroxypropanone phosphate

In the next step, FDP is broken into two three-carbon units, dihydroxyacetone phosphate (1,3-dihydroxypropanone phosphate, CH20HC0CH20P03, 5) and glyceraldehyde-3-phosphate (6), which exist in mutual equilibrium. Only the glyceraldehyde-3-phosphate is oxidized by NAD to pyruvate ion, with formation of two ATP molecules. As glycolysis proceeds, all the dihydroxyacetone phosphate is converted to glyceraldehyde-3-phosphate, so the result is the consumption of two NAD molecules and the formation of four ATP molecules per molecule of glucose. 

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