Polar, Uncharged Amino Acids
The side chains of glutamine (Gln or Q) and asparagine (Asn or N) amide derivatives of Asp and Glu, respectively, are uncharged but may participate in hydrogen bonding. Due to the reactive hydroxyl group in the side-chain Serine (Ser or S) and threonine (Thr or T) are polar amino acids, and can also participate in hydrogen bonding (as may the hydroxyl group of the aromatic amino acid Tyr).
![1073_polar uncharged amino acid.png](https://www.expertsmind.com/CMSImages/1073_polar%20uncharged%20amino%20acid.png)
The standard amino acids. (a) Polar, charged R groups, (b) polar, uncharged R groups.