Recent observations on the structure and composition of elastin.

The ultrastructural organization of elastin has been studied by scanning and transmission electron microscopy of negatively stained specimens coupled with optical diffraction analyses. Purified elastin results from a composite assembly of interwoven branched and twisted thread-like entities of decreasing diameter. The ultimate filamentous component is a rope-like structure each with an overall diameter of 3.5-4.0 nm consisting of paired filaments of indefinite length each 1.5 nm in width and periodically linked longitudinally at a varying distance of 3.5 to 4.5 nm depending on the degree of stretch.