Home Reading - Chapter 6, pp. The function of a protein can only be understood in terms of its structure. The three dimensional structures of many proteins have been determined and from these structures a few general principles can be derived.
Every protein has a unique amino acid sequence.
Secondary Structure is the spatial arrangement of the polypeptide backbone, ignoring the conformation of the sidechains. Tertiary Structure is the three dimensional structure of the entire polypeptide. Quaternary Structure refers to the three dimensional structure of proteins that are composed of two or more polypeptide chains, called subunits. However, there are significant limitations as to which angles of f and y can be used due to steric clashes between atoms. A Ramachandran Plot shows those regions of f and y where there are no steric conflicts.