Introduction and Fundamentals of Protein Structure

1. Introduction and Fundamentals of Protein Structure 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 Dr Seemal Jelani

3. 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. 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 Dr Seemal Jelani

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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 Dr Seemal Jelani

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

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

11. Three-dimensional structure of proteins Tertiary structure Quaternary structure 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） Dr Seemal Jelani

13. Close relationship between protein structure and its function Antibody Hormone receptor Example of enzyme reaction substrates A enzyme enzyme B Matching the shape to A Digestion of A! enzyme A Binding to A 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. • https://www.wisc-online.com/learn/natural-science/chemistry/bic007/peptide-bond-formation Dr Seemal Jelani