Presence of covalently attached fatty acids in rat apolipoprotein B via thiolester linkages.
Thiolester linked lipids in rat apolipoprotein B (ApoB) were examined by incubating reduced and carboxymethylated ApoB in 6 M urea buffer with [14C]methylamine at pH 8.5, 30 degrees C. It was observed that [14C]methylamine was covalently incorporated into ApoB, and there was a [14C]methylamine modified product which was lipid in nature. After extraction with organic solvents, the [14C]methylamine labeled product showed its Rf on TLC to be similar to that of the synthetic N-methyl fatty acyl amide. After purification on TLC and transesterification with 3 N methanolic HC1, methyl esters of C16:0, C18:0 and C18:1 fatty acids were identified by gas-liquid chromatography. These results suggest that rat ApoB, similar to human ApoB, contained covalently linked fatty acids through the high energy, labile thiolester bonds.
Lipoprotein and Atherosclerosis Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104.
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Kamanna
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Lee
D000818:Animals; D001055:Apolipoproteins B / Q000378:metabolism*; D002845:Chromatography; D002855:Chromatography, Thin Layer; D004952:Esters; D005227:Fatty Acids / Q000378:metabolism*; D051381:Rats; D013438:Sulfhydryl Compounds
D001055:Apolipoproteins B; D004952:Esters; D005227:Fatty Acids; D013438:Sulfhydryl Compounds