Studies in immunochemistry. 9. The oxidation of the human blood-group A substance with the periodate ion

Abstract

Fucose, galactose and a half of the total N-acetylchondrosamine residues of the A substance are oxidized by periodate at pH 5. Formaldehyde and formic acid, but no acetaldehyde or ammonia, are liberated during the oxidation. The formaldehyde and formic acid (25 hrs. oxidation) are produced in approx. equimolecular proportions and correspond to a min. molecular wt. of the order of 2000. The hydroxyamino acids, serine and threonine, are not present as terminal residues in the amino acid-containing moiety and are not involved as single molecules in simple esterification with the hydroxyl groups of the sugar units. Certain aspects of the structure of the A substance are discussed in the light of the results obtained.