1. Introduction and Fundamentals of Protein Structure
1/18/2019
Dr Seemal Jelani

2. Proteins are polypeptides, which are made up of many amino acids linked together as a linear chain
The structure of an amino acid contains a amino group, a carboxyl group, and a R group which is usually carbon based and gives the amino acid it's specific properties
1/18/2019
Dr Seemal Jelani

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Dr Seemal Jelani

4. Proteins form the very basis of life
They regulate a variety of activities in all known organisms, from replication of the genetic code to transporting oxygen, and are generally responsible for regulating the cellular machinery and determining the p
Phenotype of an organism
The observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences.
1/18/2019
Dr Seemal Jelani

5. Proteins accomplish their tasks in the body by three-dimensional tertiary and quaternary interactions between various substrates.
The functional properties depend upon the proteins three-dimensional structure
1/18/2019
Dr Seemal Jelani

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Dr Seemal Jelani

7. Proteins play key roles in a living system
Three examples of protein functions
Catalysis: Almost all chemical reactions in a living cell are catalyzed by protein enzymes.
Transport: Some proteins transports various substances, such as oxygen, ions, and so on.
Information transfer: For example, hormones.
Alcohol dehydrogenase oxidizes alcohols to aldehydes or ketones
Haemoglobin carries oxygen
Insulin controls the amount of sugar in the blood
1/18/2019
Dr Seemal Jelani

8. White: Hydrophobic, Green: Hydrophilic, Red: Acidic, Blue: Basic
20 Amino acids
Glycine (G)
Alanine (A)
Valine (V)
Isoleucine (I)
Leucine (L)
Proline (P)
Methionine (M)
Phenylalanine (F)
Tryptophan (W)
Asparagine (N)
Glutamine (Q)
Serine (S)
Threonine (T)
Tyrosine (Y)
Cysteine (C)
Asparatic acid (D)
Glutamic acid (E)
Lysine (K)
Arginine (R)
Histidine (H)
White: Hydrophobic, Green: Hydrophilic, Red: Acidic, Blue: Basic
1/18/2019
Dr Seemal Jelani

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Dr Seemal Jelani

10. Basic structural units of proteins: Secondary structure
α-helix
β-sheet
Secondary structures, α-helix and β-sheet, have regular hydrogen-bonding patterns.
1/18/2019
Dr Seemal Jelani

11. Three-dimensional structure of proteins
Tertiary structure
Quaternary structure
1/18/2019
Dr Seemal Jelani

12. Hierarchical nature of protein structure
Primary structure (Amino acid sequence) ↓
Secondary structure （α-helix, β-sheet）
Tertiary structure （Three-dimensional structure formed by assembly of secondary structures）
Quaternary structure （Structure formed by more than one polypeptide chains）
1/18/2019
Dr Seemal Jelani

13. Close relationship between protein structure and its function
Example of enzyme reaction
Hormone receptor
Antibody
substrates A
enzyme
enzyme B
Matching the shape to A
Digestion of A!
enzyme A
Binding to A
1/18/2019
Dr Seemal Jelani

14. Summary Proteins are key players in our living systems.
Proteins are polymers consisting of 20 kinds of amino acids.
Each protein folds into a unique three-dimensional structure defined by its amino acid sequence.
Protein structure has a hierarchical nature.
Protein structure is closely related to its function.
Protein structure prediction is a grand challenge of computational biology.
1/18/2019
Dr Seemal Jelani