Analysis of hog thyroglobulin. Identification of galactosamine and absence of lysinoalanine, a potential product of tyrosine coupling.

A small peak in the amino acid analysis of hog thyroglobulin was observed in the region reported for lysinoalanine and galactosamine. Since galactosamine had been previously reported absent in hog thyroglobulin, the possibility that this peak was lysinoalanine, a potential product of the coupling of two iodotyrosines, was investigated. Tests, however, showed that the material was galactosamine and that hog thyroglobulin contains no significant amount of lysinoalanine. Approximately 5 moles of galactosamine were found per mole of thyroglobulin.