Bio Chemistry

BIOCHEMISTRY 3(2+1)

Lesson 11 : Amino Acids – Classification, Properties and Peptide bonds

General Properties

1. There are 20 standard amino acids. With exception of proline, all have primary amino group and a carboxylic acid bonded to same carbon.
2. Carboxyl group and amino group all have pKa values around 2.2 and 9.4 respectively
3. Note that at physiological pH of 7, amino acids are charged as shown to left. They can act as either acid or base.
4. Also referred to as zwitterions
5. This imparts special properties e.g. some have melting points of 300 ° C, just like salts. Also very soluble in water and not organics.