It assists in this process which transforms the pyruvate into acetal aldehyde as well as releasing this CO2 molecule shown here. Now, what about step two? Well, in step two we have a different enzyme and this enzyme is known as alcohol dehydrogenase. Now, like any dehydrogenase, alcohol dehydrogenase will essentially catalyze the transfer of a Hydride group from that NADH onto this acetolaldehyde. Now, if we examine the active side of the alcohol dehydrogenase we're going to see a zinc ion. And what that zinc ion does?