Classes of globular proteins

Globular proteins have a molecular structure that has the appearance of a glob that has a 3D structure any where on a shape continuum of a sphere to a cigar. Usually the structure of a globular protein is divided into three or four levels. The primary structure is simply the sequence of amino acids forming the peptide chain. The peptide chain is folded in a repetitive fashion, and these structures with repetitive conformations are called secondary structures. Common examples of secondary structures are α-helix and β-sheets. A convenient way of classifying globular proteins is to categorize them according to the type and arrangement of secondary structures that are present, as well as the important forces that maintain the globular structure. A study of the different classes using specific examples with Jmol is found here.