Sometimes, chemical compounds can have wildly different structures and properties despite similar names. In the case of pyruvate versus pyruvic acid, however, the similarities are so profound that most chemists don't even distinguish between the two molecules, instead considering them nothing more than two forms of the same chemical.
Pyruvic acid is a small organic -- this means carbon-based -- acid with the chemical formula C3H4O3. The compound falls into a large group of organic molecules called carboxylic acids, which are characterized by having a carbon with a double bond to oxygen, a single bond to another oxygen -- which itself is also bonded to a hydrogen -- and a single bond to another carbon on the structure. While carboxylic acids aren't as strong as inorganic acids such as hydrochloric acid, they can nevertheless be quite acidic. Pyruvic acid has an acidity not unlike that of phosphoric acid.
The only difference between pyruvic acid and pyruvate is that the hydrogen atom on the carboxylic acid group has dissociated, meaning it has been lost. This leaves a negatively charged carboxylate group behind, consisting of a carbon with a double bond to one oxygen atom, a single bond to a second oxygen and a single bond to another carbon. Because of the acidity of pyruvic acid, nearly all pyruvic acid formed in the human body dissociates immediately and is found as pyruvate.
Formation of Pyruvate
Your body forms pyruvate during the process of glycolysis, explain Drs. Mary Campbell and Shawn Farrell in their book "Biochemistry." Glycolysis literally means "sugar splitting," and it's what your cells do when they begin the process of burning glucose and other sugars for energy. Each glucose molecule splits into two pyruvate molecules. This process generates a very small amount of energy, but it's possible to break down pyruvate further to yield more energy.
Uses of Pyruvate
If you're working very hard -- during a sprint effort, for instance -- you're not getting enough air to break down pyruvate, so you simply convert it into lactic acid, which yields no additional energy, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry." If you're getting sufficient air, however -- even during exercise -- you can burn pyruvate further, eventually producing carbon dioxide and water. This yields a large additional amount of energy.