Studies on the desamidation of bovine collagen.

The most important reactive groups in collagen are amino, amido, guanidino, and carboxyl, all of which are present in comparatively large numbers. It is possible to modify amide groups present in the collagen of achilles tendons and hide trimmings by desamidation (DAM). DAM causes progressive hydrolysis of the amide groups of asparagine and glutamine side chains of collagen, thereby resulting in the reduction of the amide content of collagen. Loss of amide brings about an increase in the number of free carboxyl groups in the desamidated collagen, shown by reduction in its isoionic pH. The new modified collagen, like type I bovine collagen, has high viscosity and high hydroxyproline content. The fibril formation of the modified collagen showed slight variation, and polyacrylamide gel electrophoretic analysis indicated largely alpha components, indicating destruction of inter- and intramolecular crosslinks. The swelling behavior of the modified collagen is significantly higher compared to type I bovine collagen.