The general formula for an amino acid is R-CH(NH2)-COOH.
This concise formula represents the core structure shared by all amino acids:
- Central Carbon Atom (α-carbon): This carbon atom is at the center, bonded to four different groups.
- Amino Group (-NH2): A basic group with nitrogen.
- Carboxyl Group (-COOH): An acidic group containing a carboxyl functional group.
- Side Chain (R group): This variable group is what distinguishes different amino acids from one another, giving each its unique properties. The R group can be a simple hydrogen atom (as in glycine) or a more complex structure.
Understanding the R Group
The R group, or side chain, is crucial for the diversity of amino acids. Its variations in size, shape, charge, and polarity determine an amino acid's unique chemical properties and its role in protein structure and function. Examples include:
- Glycine (Gly): R = H (Hydrogen) - Simplest amino acid
- Alanine (Ala): R = CH3 (Methyl group)
- More complex R-groups lead to amino acids with polar, nonpolar, acidic or basic properties.
The molecular weight of a basic amino acid is approximately 110 Da (Dalton). However, this varies significantly depending on the specific R group present.
The 20 common amino acids found in proteins are categorized based on their unique R group characteristics. Further exploration of individual amino acids and their specific formulas can be found in resources like the IMGT website (https://www.imgt.org/IMGTeducation/Aide-memoire/_UK/aminoacids/formuleAA/).
