LOCALIZATION AND ACTIVITY OF LYSYL OXIDASE WITHIN NUCLEI OF FIBROGENIC CELLS

Lysyl oxidase (EC 1.4.3.13) oxidizes peptidyl lysine to peptidyl aldeh yde residues within collagen and elastin, thus initiating formation of the covalent cross-linkages that insolubilize these extracellular pro teins. Recent findings raise the possibility that this enzyme may also function intracellularly. The present study provides evidence by immu nocytochemical confocal microscopy, Western blot analysis, enzyme assa ys, and chemical analyses for lysyl oxidase reaction products that thi s enzyme is present and active within rat vascular smooth muscle cell nuclei. Confocal microscopy indicates its presence within nuclei of 3T 3 fibroblasts, as well.