Proteins secreted by vascular smooth muscle cells as substrates of lysyl oxidase

The mixture of proteins secreted by neonatal rat aorta smooth muscle cells cultured in the presence of beta-aminopropionitrile was readily oxidized an d polymerized upon incubation with purified or crude preparations of lysyl oxidase, Western blot analysis indicated that these substrates included 30- 60kDa protein bands reactive with anti-elastin, presumed to be fragments de rived from tropoelastin, Thus, truncated, elastin-like as well as other pro teins accumulate in the media of these cultures which, in toto, can serve a s a conveniently prepared, highly efficient substrate for the routine assay of lysyl oxidase activity.