OPTICAL SPECTROSCOPIC DETERMINATION OF BOVINE TROPOELASTIN MOLECULAR-MODEL

Aqueous solution (CD in water) and solid state (FT-IR on a ZnSe window) spectra of bovine tropoelastin (BTPE) have been recorded and analysed in order to get additional insights into the molecular structure of its elastic elastin polymer. Conformational analyses evidenced high levels of both ordered and unordered secondary structures in the solid and solution states. The structural contents of BTPE were estimated to : alpha-helices similar to 10 %, beta-sheets similar to 30 %, beta-turns similar to 20 % and coil similar to 40 % (Kabsch and Sander definition). Moreover, CD experiments showed the possibility for the molecule to be folded in an all-beta configuration with short and / or distorted sheets. As this structural features were formerly predicted for BTPE, our experimental data allowed us to suggest a similar folding for monomeric elastin. Our all-beta structural proposal for BTPE is discussed according to bovine elastin structure-elasticity relationship.