Introduction to protein structure

Levels of Protein Structure

spinqualitylabelsall models Structure of Hemoglobin (PDB entry 1A3N) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Proteins are condensation polymers of amino acids. The primary structure is the amino acid sequence. The secondary structure is the local structure over short distances. This level of structure is stabilized by hydrogen bonds along the backbone. These secondary structures pack together to form the overall form of the entire peptide chain, called the tertiary structure. Some proteins, such as the displayed hemoglobin molecule, have more than one polypeptide chain that associate to form the functional unit of the protein; this is called quaternary structure. Questions based upon these scenes: What is the primary sequence shown in the first link? Is the secondary structure shown an alpha helix or beta sheet? The ith C=O of the backbone is hydrogen bonded to which N(-H) (use i +/- # to represent the number)? What atom does this program NOT show? What color is used to represent alpha helices? How many alpha helices are present in the single peptide chain shown? How many polypeptide chains make up the quaternary structure?

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