The carbohydrate portion of prothrombin fragment 1 has been removed by fluorolysis in anhydrous HF. The deglycosylated protein retains its calcium- and membrane-binding properties. The slow, calcium-dependent protein transition monitored by changes in intrinsic protein fluorescence remains intact for the aglycoprotein. Calcium-dependent protein-membrane binding is also observed and can be quantitatively reversed with EDTA. The major alteration resulting from carbohydrate removal is the degree of protein self-association. Both the normal and deglycosylated proteins undergo a rapid self-association which approaches a dimer in the presence of calcium. This self-association is independent of the slow change in intrinsic fluorescence. The deglycosylated protein then undergoes a secondary self-association with kinetics identical with the fluorescence change. This secondary self-association also occurs on the membrane surface. This suggests that the calcium-dependent conformational change exposes a site on the protein which functions in secondary self-association. The carbohydrate apparently masks this site in the native molecule.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|State||Published - Aug 10 1980|