Variation of elastin fluorescence with method of preparation: determination of the major fluorophore of fibrillar elastin.
The variation of fluorescence of two fibrillar elastins as a result of preparation methods was studied and the major common fluorophore was identified. Dilution of acid-hydrolyzed bovine ligament elastin 1:2500 (g:ml) overcame inner filter effects (IFE) to reveal fluorescence excitation and emission maxima of 330/408 nm. An IFE effect observed in elastase-solubilized elastin was unresponsive to dilution. Elastase-solubilized elastin had maximal fluorescence at 338/410 nm (pH 2.3) and 325/394 nm (pH 7.4), and the fluorescence intensity was 35-40% of that of the acid-hydrolyzed elastin. Changes in fluorescence that occurred when an acid hydrolysate was evaporated to dryness were prevented by evaporation to a volume not less than 15 ml. As a result, there was an almost two-fold increase in the yield of a fluorophore with spectral maxima near 340/400 nm. Chick aorta elastin purified by enzymatic methods also contained substantial amounts of this fluorophore. It is concluded that the compound with fluorescence of 340/400 nm is the major common fluorophore of postnatal fibrillar elastins.