Converts glyceraldehyde-3-phosphate (G3P) into 1,3-Bisphospho-D-glycerate (BPG). This is a vital step in glycolysis (as are all the steps) but the enzyme has some other activities. These include binding viral RNA which sometimes inhibits and sometimes promotes viral growth. Product:


The mechanism:

R-C=O -Cys-SH-> R-C-S-Cys (a thiohemiacetal) -NAD-> R-C=O
  |                  |                                      |
  H                  H                      (thioester) Cys-S
The cys is then deacetylated by a phosphate. In ALDH, the same mechanism occurs, but the deacetylation step uses a water molecule to hydrolyse.