The linkage of sialic acid in the Ehrlich ascites-carcinoma cell surface membrane.

1. The sialic acid content of fresh and fixed Ehrlich ascites cells was determined by incubation with neuraminidase and analysis of the supernatants. 2. The content of sialic acid was also determined on ultrasonically disrupted cells either with or without prior neuraminidase treatment, and the location of sialic acid in the cell is discussed. 3. The sialic acids, cleaved from cells by neuraminidase, were identified chromatographically. 4. Proteolytic enzymes were used to isolate from cells a mucopeptide containing sialic acid and galactosamine in almost equimolar proportions. 5. The nature of the carbohydrate-amino acid bond in the muco-peptide was investigated by alkaline hydrolysis. 6. A suggestion is made about the particular amino acids involved in the sugar-peptide bond.