In: Biology
Compare and contrast the properties of any two different amino acid side chains and explain how their chemical properties contribute to the structure of a protein.
Basic amino acid side chains are found in arginine (arg), Lysine (Lys) and Histidine (His).
The structure above is the structure if arginine. Here the CNHNH2 is the basic side chain. This side chain has ammonia which is a base. The pKa is high and thus binds protons by gaining a positive charge. Arginine helps in forming salt bridges in protein structure and they pair with a negatively charged amino acid. Also helps to form hydrogen bonds.
The acidic amino acid side chain aspartate and glutamate. The structure of aspartate is:
Here the -COOH denotes the acidic side chain group. It contains the alpha carboxylic acid group. Aspartate is present on the surface of the proteins in general and is exposed to the aqueous environment. They usually form a bond with a positively charged amino acid.