Various aliphatic and aromatic amines are oxidized by sodium metaperiodate and these reactions have been studied quantitatively in acidic, unbuffered and basic media. Significant differences have been observed between the behaviour of aliphatic and aromatic amines. Certain compounds also behaved differently under acidic and basic conditions. These reactions are related to the periodate oxidation of amino acids and, from observations on a number of glycine derivatives, a reaction mechanism is proposed for this process.
1. The structure of the carbohydrate component of the glycopeptide isolated from the proteolytic digest of ovalbumin has been investigated by chemical and enzymic methods. 2. The results are consistent with the presence of a single carbohydrate prosthetic group, linked through its reducing end group to the peptide chain. 3. Further, all the 2-amino-2-deoxy-d-glucose units appear to be in the N-acylated form, the phenolic hydroxyl group of tyrosine is free and the omega-carboxyl group of aspartic acid is substituted. 4. The carbohydrate component has a branched-chain structure, the two non-reducing ends being terminated by a d-mannopyranosyl and a 2-acetamido-2-deoxy-d-glucopyranosyl residue respectively. 5. The terminal d-mannopyranosyl unit is probably linked through at least one other d-mannopyranosyl residue to the remainder of the carbohydrate.
The oligosaccharide units of a type K and a type L IgA immunoglobulin have been examined. The two proteins differed in their content of 6-deoxy-l-galactose and N-acetylneuraminic acid, and in the d-mannose/d-galactose ratio. With glycopeptides prepared from the type K protein, specific glycosidases liberated the N-acetylneuraminic acid and 7-8 residues of 2-acetamido-2-deoxy-d-glucose, and mild acid hydrolysis released most of the 6-deoxy-l-galactose. The type K immunoglobulin appeared to contain 3 oligosaccharide units, whereas the type L protein probably contained 3 or more units.
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