The isolation and characterization of a glycoprotein from human thoracic aorta.

1. A glycoprotein extracted by cold alkali from the walls of human aorta was purified by chromatography on DEAE-cellulose. 2. The compound was electrophoretically homogeneous and essentially so by chromatography on DEAE-cellulose. Ultracentrifugal examination revealed two components, and it is suggested that the faster-sedimenting component represents an aggregated form of the glycoprotein. 3. Glycoprotein preparations contained approx. 8% of carbohydrate. Digestion with Pronase yielded a glycopeptide fraction containing all the carbohydrate of the glycoprotein. The glycopeptide, of molecular weight about 7800, contained sialic acid, galactose, mannose, fucose and hexosamine in the approximate molar proportions 5:10:5:2:11. Sialic acid was terminal with respect to the polysaccharide chains. 4. Both elastase and elastomucoproteinases exhibited proteolytic activity towards the glycoprotein. Studies by other investigators have led to the conclusion that elastomucoproteinases attack protein-carbohydrate complexes occurring in intimate association with elastin in aorta and other tissues, and it is suggested that the glycoprotein may be identified with one of these compounds.