Protein Structure and Function PDF

PROTEIN SOFEE AKHLAK LEARNING OUTCOME 1. Define protein 2. State the functions of protein 3. List the 20 common amino acids 4. Illustrate the chemical structure of amino acid 5. State the different chains of amino acids 6. Describe the classification of amino acids 7. Explain the 4...

PROTEIN SOFEE AKHLAK LEARNING OUTCOME 1. Define protein 2. State the functions of protein 3. List the 20 common amino acids 4. Illustrate the chemical structure of amino acid 5. State the different chains of amino acids 6. Describe the classification of amino acids 7. Explain the 4 levels of structural organization of protein INTRODUCTION METABOLISM Is the sum of all the chemical processes that occur in the body Catabolism – breakdown of complex chemical substances into simpler components Anabolism – the building up of complex chemical substances from smaller/simpler components E.g. – digestive processes catabolize (split) proteins in food into amino acids – used in anabolism (build) new proteins that makes up body structure. Protein Definition: Large molecules – macromolecule Contains carbon, hydrogen, oxygen, and nitrogen Some has sulfur Adult body – 12-18% protein Functions of protein: Amino acids The monomer (building blocks) of protein 20 different types of amino acids forms the building blocks of protein The liver synthesizes 10 10 essential amino acids - diet Common amino acids Structure An amino group (NH2) A carboxyl group (COOH) A hydrogen atom (H) Side chain (R group) – variable side chain Central carbon Covalent bond joining amino acids – peptide bond Form various length – 100 to 50 000 amino acids The chain is then folded to form a three dimensional (coiled) protein molecule - subunit Protein subunit Chain of amino acids: Dipeptide – 2 amino acid Tripeptide – 3 amino acids Peptide – 4-9 amino acids Polypeptide – 10 to 2000 or more amino acids Classification of amino acids Classified according to its capacity to interact with water 1. Neutral non polar amino acid No charge Hydrophobic – interacts poorly with water 2. Neutral polar amino acid No charge Hydrophilic – water loving, interacts with water 3. Acidic amino acid Negatively charged 4. Basic amino acid Positively charged  Although there are only 20 amino acids, they can combine to form numerous types of protein with unique structure and function  Different proteins have different kinds and number of amino acids arranged to form a chain of amino acid Levels of protein structural organization Proteins have 4 levels of structural organization 1. Primary structure Linear sequence of amino acids connected by peptide bond - polypeptide 2. Secondary structure Packing of polypeptide chain: i. α helices ii. β sheets Stabilized by hydrogen bond between peptide bond 3. Tertiary structure Results from folding of secondary structure 4. Quaternary structure Arrangement of multiple polypeptide termed as subunit Conformation:  refers to completely folded protein  Must have went through primary, secondary, tertiary and quaternary level of folding  Breakdown at any level of folding causes misfolding – disease happens END