Presence of heparan sulfate in the fat globule membrane of bovine and human milk.

Abstract

Glycosaminoglycans were isolated from bovine and human milk fat globule membrane (MFGM) preparations and characterized. The amount of glycosaminoglycans in human MFGM protein fraction was 510 times higher than that in bovine MFGM protein fraction. On Dowex-1 column chromatography most of the glycosaminoglycans were eluted with 1 M and 3 M NaCl. Cellulose acetate electrophoresis, chondroitinase digestion and nitrous acid degradation indicated that the major glycosaminoglycan in both bovine and human MFGM was heparan sulfate. Bovine MFGM was shown to contain chondroitin sulfate A/C in addition to heparan sulfate. The glycosaminoglycan composition of bovine colostral MFGM was similar to that of bovine normal MFGM. The glycosaminoglycan fraction prepared from MFGM of human colostrum, however, did not contain heparan sulfate, suggesting some compositional changes in glycosaminoglycans during the lactation period.