1. Amino Acids and Protein Chemistry
For nursing Faculty
By Dr Rehab Omer
Faculty of Medicine, U of D

2. Definitions:
Amino acids are compound containing amino and carboxylic acid
building blocks of protein.
Proteins are polymers of amino acids linked by peptide bond.

3. Importance of amino acids:
- building blocks of proteins
-energy source
Precursors for non protein specialized products

4. Importance of protein:
1- enzymes 2- hormones
3- structural
4- transport 5- immunoglobulins
6- clotting factors
7- complements
8- buffers

5. Proteins are formed of a set of 20 amino acids
Proteins are formed of a set of 20 amino acids. They are called standard amino acids. There are more than 300 amino acid in nature, only these 20 amino acids are found in protein from all living sources (bacteria, animal and plant). The general formula is:

7. Structure of Amino Acids
The α-carbon of an amino acid is attached to four different chemical groups and is, therefore, a chiral or optically active carbon atom
Glycine is the exception because its α-carbon has two hydrogen substituents and, therefore, is optically inactive
All amino acids found in proteins are of the L-configuration

8. D& L amino acids:

9. Classification of amino acids according to their side chain

10. Amino Acids with Aliphatic R-Groups
Alanine
Valine
Glycine
Leucine
Isoleucine

11. Non-Aromatic Amino Acids with Hydroxyl R-Groups
Serine
Threonine
Sulfur containing Amino acids
Cysteine
Methionine

12. Acidic Amino Acids and Their Amides
Aspartic Acid
Asparagine
Glutamic Acid
Glutamine

13. Basic Amino Acids
Arginine
Lysine
Histidine

14. Aromatic Amino Acids
Phenylalanine
Tyrosine
Tryptophan

15. Imino Acid
Proline

16. Classification by solubility
There are two broad classes of amino acids based upon whether the R-group is
1. Hydrophobic
2. Hydrophilic.

17. The hydrophobic amino acids
The hydrophobic amino acids tend to repel the aqueous environment and, therefore, reside predominantly in the interior of proteins.
The side chain of this class of amino acids does not ionize nor participate in the formation of H-bonds.

19. The hydrophilic amino acids
The hydrophilic amino acids tend to interact with the aqueous environment; polar or charged side chain.
They are often involved in the formation of H-bonds
They are predominantly found on the exterior surfaces of proteins or in the reactive centers of enzymes

21. Dietary Classification of Amino Acids
Some amino acids can be formed from metabolic intermediates in the mammalian cells, thus are not necessary taken in food (Dietary non-essential) .
Other amino acids must be obtained from diet, thus they are termed (Dietary essential)

23. The Peptide Bond
Peptide bond formation is a condensation reaction leading to the polymerization of amino acids into peptides and proteins.
Peptides are small consisting of few amino acids.
many hormones,, antitumor agents and neurotransmitters are peptides.
Proteins are polypeptides of greatly divergent length and amino acid composition.

26. Biochemistry of Proteins
Protein Structure

27. Levels of protein structure:
1- primary structure
2- secondary structure
3- tertiary structure
4- quaternary structure