Abstract
In our previous experiments some properties of glycopeptide isolated from immune lactoglobulin were reported.
The present paper reports on the preparation and the properties of glycopeptide obtained from κ-casein which contains carbohydrate. κ-Casein was prepared from whole casein by the urea-sulfuric acid method of Zittle and Custer, and it was digested by Pronase-P repeatedly. The glycopeptide of molecular weight 3, 459 was isolated from the digested material by gel filtration on Sephadex and DEAE cellulose chromatography. Judging from hexose recovery approximately twenty six percents of the total hexose of κ-casein were recovered from Pronase digest.
Study of the glycopeptide indicated the presence of 15 amino acid residues, including 5 threonine and 2 serine residues and 4, 3 and 3 residues of galactese, galactosamine and sialic acid respectively.
Glycopeptide soluble in 12% trichloroacetic acid was obtained after rennin digestion of κ-casein for comparison with that of Pronase digest. The content of carbohydrate in the glycomacropeptide was not so high, but the ratio of galactose, galactosamine and sialic acid to each other was nearly equal to that in the glycopeptide isolated from Prenase hydrolysate.
