Glutamine
Glutamine (symbol Gln or Q) is an α-amino acid that is used in the biosynthesis of proteins. Its side chain is similar to that of glutamic acid, except the carboxylic acid group is replaced by an amide. It is classified as a charge-neutral, polar amino acid. It is non-essential and conditionally essential in humans, meaning the body can usually synthesize sufficient amounts of it, but in some instances of stress, the body's demand for glutamine increases, and glutamine must be obtained from the diet. It is encoded by the codons CAA and CAG.
Serine
-serine was thought to exist only in bacteria until relatively recently; it was the second amino acid discovered to naturally exist in humans, present as a signaling molecule in the brain, soon after the discovery of -aspartate. Had amino acids been discovered in humans sooner, the glycine site on the NMDA receptor might instead be named the -serine site. Apart from central nervous system, -serine plays a signaling role in peripheral tissues and organs such as cartilage, kidney and corpus cavernosum.