Blood catalsase polymorphism: some immunological aspects.

The immunological properties of the erythrocyte catalase of mice-normal (wild type) strain, one lacking catalase (acatalasemic), and four with only slight catalase activity (hypocatalasemic strains)-have been investigated. Agardiffusion tests and antigen titration of red-cell lysates against rabbit antiserum to catalase from normal mouse blood showed that immunologically identical catalase protein was present in large amounts in the acatalasemic as well as in the hypocatalasemic mutant strains. Despite lack of catalatic activity, the erythrocytes lacking catalase as well as those with only a little catalase contain catalase protein that has been modified at the site of enzyme activity, although the antigenic determinants are identical with those of normal catalase protein. This mutation is purely structural, being characterized by modification of the enzyme active site but not of the antigenic site.