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In this chapter, you will: Define protein conformation and native conformation, know the difference between a simple and conjugated protein, know what homomeric and heteromeric proteins are, know what monomeric and multimeric proteins are, know the general properties of fibrous and globular proteins, know the 4 levels of protein structure, know the 4 non-covalent forces that are important in determining protein structure,. | Chapter 4 Protein 3-Dimensional Structure and Function Terminology Conformation – spatial arrangement of atoms in a protein Native conformation – conformation of functional protein Protein Classification Simple – composed only of amino acid residues Conjugated – contain prosthetic groups (metal ions, co-factors, lipids, carbohydrates) Example: Hemoglobin – Heme Protein Classification One polypeptide chain - monomeric protein More than one - multimeric protein Homomultimer - one kind of chain Heteromultimer - two or more different chains (e.g. Hemoglobin is a heterotetramer. It has two alpha chains and two beta chains.) Protein Classification Fibrous – polypeptides arranged in long strands or sheets water insoluble (lots of hydrophobic AA’s) strong but flexible Structural (keratin, collagen) Globular – polypeptide chains folded into spherical or globular form water soluble contain several types of secondary structure diverse functions (enzymes, regulatory proteins) keratin collagen . | Chapter 4 Protein 3-Dimensional Structure and Function Terminology Conformation – spatial arrangement of atoms in a protein Native conformation – conformation of functional protein Protein Classification Simple – composed only of amino acid residues Conjugated – contain prosthetic groups (metal ions, co-factors, lipids, carbohydrates) Example: Hemoglobin – Heme Protein Classification One polypeptide chain - monomeric protein More than one - multimeric protein Homomultimer - one kind of chain Heteromultimer - two or more different chains (e.g. Hemoglobin is a heterotetramer. It has two alpha chains and two beta chains.) Protein Classification Fibrous – polypeptides arranged in long strands or sheets water insoluble (lots of hydrophobic AA’s) strong but flexible Structural (keratin, collagen) Globular – polypeptide chains folded into spherical or globular form water soluble contain several types of secondary structure diverse functions (enzymes, regulatory proteins) keratin collagen catalase Protein Function Catalysis – enzymes Structural – keratin Transport – hemoglobin Trans-membrane transport – Na+/K+ ATPases Toxins – rattle snake venom, ricin Contractile function – actin, myosin Hormones – insulin Storage Proteins – seeds and eggs Defensive proteins – antibodies 4 Levels of Protein Structure Non-covalent forces important in determining protein structure van der Waals: 0.4 - 4 kJ/mol hydrogen bonds: 12-30 kJ/mol ionic bonds: 20 kJ/mol hydrophobic interactions: <40 kJ/mol 1o Structure Determines 2o, 3o, 4o Structure Sickle Cell Anemia – single amino acid change in hemoglobin related to disease Osteoarthritis – single amino acid change in collagen protein causes joint damage Classes of 2o Structure Alpha helix B-sheet Loops and turns 2o Structure Related to Peptide Backbone Double bond nature of peptide bond cause planar geometry Free rotation at N - aC and aC- carbonyl C bonds Angle about the C(alpha)-N bond is denoted phi (f) Angle about the C(alpha)-C bond is .
