Abstract
Flagellin (mol. wt. 40,000) from S. adelaide organisms was acetoacetylated to varying extents with diketene (acetoacetic anhydride). Chemical studies demonstrated that the amino groups of flagellin were more readily acetoacetylated than the hydroxyl groups. Several antigenic tests revealed that as flagellin was acetoacetylated to increasing extents there was a steady decline in the affinity of the molecule for anti-flagellin antibodies.