The objective of this research is to gain a better insight into the physical and chemical nature of the thyroglobulin molecule and its role in the biosynthesis, storage and release of thyroid hormones. Among the specific goals of the project will be a study of the distribution of oligosaccharide moieties and iodinated amino acids through the polypeptide sequence of thyroglobulin as reflected in tryptic peptides and the determination of amino acid sequences in the vicinity of these moieties. In addition, a continuation and extension of ultracentrifugation and rotational diffusion measurements of thyroglobulin and thyroglobulin containing complexes is proposed. A study of a model system for thyroxine biosynthesis utilizing micelles containing N-palmityldiiodotyrosine and related derivatives to simulate the environment of a globular protein surface will be continued. Fractionation of protein-SDS complexes is being carried out in order to isolate the various polypeptide fragments derived from the thyroglobulin structure and to determine the distribution of thyroid hormones and oligosaccharide within their structures.