Proteins Secreted by Vascular Smooth Muscle Cells as Substrates of Lysyl Oxidase

Abstract

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