The document discusses the four levels of protein structure: primary, secondary, tertiary, and quaternary. It provides examples of common secondary structures like alpha helices and beta sheets. Tertiary structure describes the 3D arrangement of all atoms in the protein. Quaternary structure refers to the association of multiple polypeptide chains. The document outlines various experimental techniques used to determine protein structure like X-ray crystallography and NMR.

1. Chapter Four The Three-Dimensional Structure of Proteins

7.  -Helix (Cont’d)

10.  -Pleated Sheet (Cont’d)

14. Schematic Diagrams of Supersecondary Structures

18. Comparison of Shapes of Fibrous and Globular Proteins

21. Forces That Stabilize Protein Structure

24. High resolution method to determine 3˚ structure of proteins (from crystal) Diffraction pattern produced by electrons scattering X-rays Series of patterns taken at different angles gives structural information Determines solution structure Structural info. Gained from determining distances between nuclei that aid in structure determination X-Ray and NMR Data

26. The Structure of Myoglobin

27. Oxygen Binding Site of Myoglobin

29. Denaturation of a Protein

30. Several ways to denature proteins • Heat • pH • Detergents • Urea • Guanadine hydrochloride Denaturation and Refolding in Ribonuclease

33. Structure of Hemoglobin

35. Oxy- and Deoxyhemoglobin

37. Predicting Protein Structure

39. Hydrophobic and Hydrophilic Interactions in Proteins