An analysis of the structure and antigenicity of different forms of XXXX thyroid peroxidase.

@entity1 @entity5787 @entity2743 @entity1669 @entity535 @entity2621 @entity1520 @entity214
Thyroid peroxidase ( @entity5787 ) is an important enzyme in the production of thyroid hormone and one of the major autoantigens in @entity1669 . The gene for @entity1 thyroid peroxidase encodes a single 933 @entity535 polypeptide chain. However, several reports have suggested that it exists in both high- and low-molecular-weight forms and the exact structure of the native enzyme is not known. We examined the structure of @entity5787 using two monoclonal antibodies against different portions of @entity5787 , a polyclonal mouse antiserum raised against a 300 @entity535 fragment of @entity5787 and autoantibodies directed against @entity5787 obtained from @entity1 with @entity1669 . Western blots performed under nonreducing conditions identified three bands of approximately 220-230 kDa and two bands of 105 and 110 kDa that appeared to be immunologic @entity5787 . After reduction, the @entity5787 activity migrated as a smear of bands from 105 to 110 kDa, suggesting that the higher molecular weight form of the enzyme is a @entity1520 -linked dimer. @entity1 with @entity1669 showed higher rates of recognition of the dimer than the reduced monomer when serologic reactivity was analyzed by Western blots. Eighty-three percent (40 of 48) of @entity1 with @entity2743 and 76% (34 of 45) of @entity2621 @entity1 recognized the dimer form of @entity5787 , while 48% (23 of 48) of Graves' and 60% (27 of 45) of @entity2621 @entity1 recognized reduced monomer @entity5787 , even though both forms were denatured with @entity214 . Antibodies against different portions of the @entity5787 chain all bound to the 105 kDa bands, indicating that the @entity5787 chain is not bisected during posttranslational processing.(ABSTRACT TRUNCATED AT 250 WORDS)
