Elastase digestion and biochemical analysis of the elastin from an elastofibroma.

Elastin from both elastofibroma and control skin samples was analyzed by means of pancreatic elastase digestion and subsequent biochemical studies, such as for elastin content and amino acid composition. Elastin of elastofibroma was more resistant to elastase digestion than that of controls. Elastin content was increased almost twice (wet weight) or three times (dry weight) in elastofibroma. The amino acid composition had the characteristics of elastin; however, the cross-linking amino acids such as desmosine, isodesmosine, and lysinonorleucine were increased in elastofibroma when compared with controls. An electron microscopic study showed that the interspersed cells had prominent intermediate filaments without any periodicity, pinocytotic vesicles, rough endoplasmic reticulum, and other organelles. These cells were considered to be fibroblasts not myofibroblasts. Therefore, it could be supposed that fibroblasts newly form an elastin that has a slightly different amino acid composition from that of controls.