Coenzyme A-dependent modification of fatty acyl chains of rat liver membrane phospholipids: possible involvement of ATP-independent acyl-CoA synthesis.
Certain species of fatty acyl chains of microsomal lipids from rat hepatocytes underwent desaturation when the microsomal fraction was incubated with CoA and NADH. For instance, 18:0, 18:2(n-6), and 20:3(n-6) incorporated into membrane lipids were gradually converted to 18:1(n-9), 18:3(n-6), and 20:4(n-6), respectively. Further, 20:5(n-3) and 18:3(n-6) were metabolized to 22:5(n-3) and 20:4(n-6) respectively, through chain elongation or chain elongation plus subsequent desaturation when malonyl-CoA was present. In contrast to esterified fatty acids, negligible change was observed for fre fatty acids under the same experimental conditions. It is apparent that ATP-independent acyl-CoA synthesis is implicated in such enzymatic modification of fatty acyl chains. The presence of either gel-filtered cytosol or bovine serum albumin markedly potentiated the reaction. However, the addition of ATP and Mg2+ did not accelerate the overall reaction induced in the presence of CoA alone. These results suggest that the pathway of CoA-dependent/ATP-independent modification of fatty acyl chains is sufficiently active to account for the desaturation and chain elongation of fatty acids esterified in membrane lipids, especially phospholipids, of living cells.
Sugiura
T
T
Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan.
Kudo
N
N
Ojima
T
T
Kondo
S
S
Yamashita
A
A
Waku
K
K
D000214:Acyl Coenzyme A / Q000096:biosynthesis; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003065:Coenzyme A / Q000378:metabolism*; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008297:Male; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D000214:Acyl Coenzyme A; D005227:Fatty Acids; D008563:Membrane Lipids; D010743:Phospholipids; D009243:NAD; D000255:Adenosine Triphosphate; D008274:Magnesium; D003065:Coenzyme A