Glutamic Acid is a non essential amino acid. When glutamic acid combines with ammonia, a waste product of metabolic activity, it is converted into glutamine. Glutamic acid itself is synthesized from the amino acids arginine, ornithine and proline.

Glutamine is the most abundant amino acid in the body, however because it can be synthesized it, too, is considered a 'non essential' amino acid (those of us who use it, however, think otherwise ) Glutamine is responsible for roughly 35% of the nitrogen that gets into the muscle cell. Glutamine literally drives muscle building nitrogen into the muscle cell where it is synthesized for growth.

Glutamine also plays a role in the release of human growth hormone.

Glutamine peptides are more stable in liquids and make it through the stomach to the blood more readily - where you want them if you're using glutamine for muscle recovery. Glutamine breaks down rather quickly when it's mixed with liquid so the peptide form is more desirable (again if higher concentration in the blood are what you want).

You'll find that soy protein shakes have a higher glutamine content than whey (they also contain more BCAA's).

Cheers,
Nat