The charge of a side chain in a molecule can be either positive, negative, or neutral.
Positive side chains are typically found in amino acids like lysine and arginine, which contain positively charged groups.
Negative side chains are commonly found in amino acids like aspartic acid and glutamic acid, which contain negatively charged groups.
Neutral side chains can be further categorized as polar or nonpolar. Polar neutral side chains contain groups that can form hydrogen bonds, like those found in serine and threonine. Nonpolar neutral side chains lack these groups and are hydrophobic, like those found in alanine and valine.
The charge of a side chain plays a crucial role in the structure and function of proteins. For example, charged side chains can participate in electrostatic interactions, which help to stabilize protein folding. They can also interact with other molecules, such as DNA or other proteins.
Examples:
- Lysine: Has a positively charged amino group.
- Glutamic acid: Has a negatively charged carboxyl group.
- Alanine: Has a nonpolar methyl group.
