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Biosynthesis of medium‐chain triacylglycerols and phospholipids by HepG‐2 cells
Author(s) -
Pakula Ronit,
Rubin Moshe,
Moser Asher Moshe,
Lichtenberg Dov,
Tietz Alisa
Publication year - 1997
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-997-0063-7
Subject(s) - chemistry , clinical chemistry , biosynthesis , metabolism , lipidology , biochemistry , chromatography , phospholipid , enzyme , membrane
In an attempt to understand the metabolism by the liver of fatty acids (FA) of different chain length, we have studied the incorporation of [1‐ 14 C]‐labeled C 2 , C 8 , C 10 , C 12 , and C 16 into cellular lipids by HepG‐2 cells. Over 90% of the radiolabeled FA were detected in phospholipids (PL) and triacylglycerols (TAG). The incorporation of C 12 and C 16 was three to four times higher than that of C 8 and C 10 (and reached 35 nmoles per mg protein after 1.5 h). The radioactivity of C 2 , C 8 , and C 10 was recovered mainly in PL. C 12 and C 16 were incorporated at approximately equal amounts into PL and TAG. The radioactivity of both C 2 and C 8 was recovered exclusively in long‐chain FA, suggesting oxidation of C 8 into C 2 units prior to FA synthesis. C 10 likewise yielded mainly long‐chain FA. However 10% of unchanged C 10 was found in PL and up to 30% in TAG. 14 C–C 12 was largely incorporated unchanged. Under these conditions, the presence of C 10 and C 12 in PL and TAG was shown also by gas‐liquid chromatography. In the presence of either C 2 , C 8 , or C 10 , up to 30% of 14 C‐monounsaturated FA were detected in PL and TAG. With C 12 and C 16 , the fraction of 14 C‐monounsaturated FA was much smaller suggesting that extensive desaturation occurred during de novo synthesis.