【正文】 as discovered by Frederick Sanger. He was given a Nobel prize in 1958. Primary structure is described by the sequence of Amino Acids in the chain SECONDARY STRUCTURE Secondary structure describes the way the chain folds. Some chains fold in a repeating spiral . Alpha Helix Some chains fold in a series of zig zags . Beta Pleated Sheets Some chains have other binations, as well as both those above. The Alpha Helix Right handed Left handed Beta Pleated Sheet The dotted lines are hydrogen bonds which bind the strands together, making this a strong flat fibrous protein. In Silk, these sheets stack together like a pile of corrugated iron. Hbonds between the sheets make silk a very strong structural protein PolyLProline These strands contain repeating units of the Amino Acid, Proline. When three such strands wrap around each other like rope they make a strong fibrous protein, similar to Collagen. Collagen is found in skin, ligaments and tendons COLLAGEN An important ponent of animal connective tissue. Collagen is made from three strands consisting mainly of Glycine an