Circular dichroic studies of a desmosine crosslinked peptide reveal a hitherto undescribed elastin spectrum possessing a weak negative band at 230–235 nm, a weak positive band at 215 nm, and a maximum negative band at 190 nm. The spectrum is sensitive to both pH and temperature displaying increased ellipticity of the 215‐nm band at acidic pH and low temperature. The general shape of the spectrum and its behaviour toward temperature changes suggest the presence of an extended helical conformation. Susceptibility of insoluble elastin to digestion with chymotrypsin is increased tenfold at low temperature (4°C), supporting the contention that the conformational change of the type described above occurs in insoluble elastin. Such changes in conformation would result in increased availability of aromatic amino‐acid resiudues to peptide bond cleavage.