BOVINE ELASTIN AND KAPPA-ELASTIN SECONDARY STRUCTURE DETERMINATION BYOPTICAL SPECTROSCOPIES

Elastin is the macromolecular polymer of tropoelastin molecules respon sible for the elastic properties of tissues. The understanding of its specific elasticity is uncertain because its structure is still unknow n. Here, we report the first experimental quantitative determination. of bovine elastin secondary structures as well as those of its corresp onding soluble K-elastin. Using circular dichroism and Fourier transfo rm infrared and near infrared Fourier transform Raman spectroscopic da ta, we estimated the secondary structure contents of elastin to be sim ilar to 10% alpha-helices, similar to 45% beta-sheets, and similar to 45% undefined conformations. These values were very close to those we had previously determined for the free monomeric tropoelastin molecule , suggesting thus that elastin would be constituted of a closely packe d assembly of globular beta structural class tropoelastin molecules cr osslinked to form the elastic network (liquid drop model of elastin ar chitecture). The presence of a strong hydration shell is demonstrated for elastin, and its possible contribution to elasticity is discussed.