Lipid modifications of microsomes isolated from villus and crypt zones of bovine intestinal mucosa: relationship with fatty acid binding protein.

The present studies were conducted to examine the fatty acid composition of microsomal lipids of bovine small intestine. Microsomes and cytosol were isolated from mucosal scrapings enriched with villus and crypts cells, and the following studies were conducted to: 1) analyse fatty acids from microsomal lipids; 2) incorporate 1-14C oleic acid to microsomal lipids; and 3) bind 1-14C oleic acid to cytosolic proteins of villus and crypt zone. The results of these studies demonstrated that: (1) the major unsaturated fatty acids of microsomes were oleic (C18:1 n-9), linoleic (C18:2 n-6) and arachidonic acids (C20:4 n-6), which increased from crypt to villus tip of the bovine intestinal mucosa; (2) gel filtration chromatography indicated that the low-molecular weight cytosolic proteins obtained from superficial mucosal scrapings contained the greatest oleic acid binding activity; (3) the incorporation of 1-14C oleic acid to microsomes was higher in phospholipids, triglycerides and cholesterol esters from villus than in crypts zones; (4) the protein content of cytosol and microsomes was longer in villus zones than in crypts zones; (5) the peroxidizability index showed the highest value in villus microsomes.