Buffalo thyroglobulin.

1. Buffalo thyroglobulin is the major iodoprotein of buffalo thyroid with a sedimentation coefficient of 19 S and an apparent molecular mass of 685 kDa. 2. The protein is rich in iodine (1-2%) and thyroxine bound iodine (75%), unlike thyroglobulins of other mammalian species. 3. As a glycoprotein, it has the same sugar residues as noted for other thyroglobulins, and the total carbohydrate content varies from 8.41 to 9.61%. 4. Amino acid composition of buffalo thyroglobulin is similar to other species. However, the protein has 2% more proline than other mammalian thyroglobulins. 5. Glutamic acid is the sole N-terminal amino acid of buffalo thyroglobulin, in contrast to aspartic acid or asparagine for several other species. 6. The quaternary structure of the protein appears to be comprised of eight non-identical subunits.