Abstract
The effect of ATP on the microsomal desaturation of linoleic acid to γ-linolenic acid was studied in a system in vitro with the following results: (1) preincubation of rat liver microsomes with ATP alone in N2 or in the presence of CoA and Mg++ followed by subsequent incubation with 1-14C-linoleic acid plus NADH in O2 resulted in enhancement of 1-14C-linoleic acid desaturation when compared with control samples in which no preincubation was performed; (2) the preincubation of the microsomes with ATP, Mg++ and CoA in the presence of 1-14C-linoleic acid decreased the desaturation of the labeled acid to γ-linolenic acid upon subsequent incubation with NADH, as a consequence of incorporation of the acid into the microsomal lipids; (3) the increase of linoleic acid desaturation depended on the ATP concentration during preincubation and followed a sigmoidal curve. It was specific for ATP, and neither GTP, CTP, ADP nor AMP produced a similar effec. However, GTP or CTP could replace ATP as a cofactor in the microsomal desaturation of free linoleic acid to γ-linolenic, suggesting that directly or indirectly they may activate conversion of the free acid to linoleyl-CoA; (4) preincubation of microsomes with ATP activated the acylation of CoA. However, this activation showed no quantitative correlation with enhancement of the desaturation reaction; (5) addition of ATP also stimulated conversion of linoleyl-CoA to γ-linolenic acid. This enhancement was not related to inhibition of the linoleyl-CoA hydrolase; (6) however, in spite of these results, preincubation with ATP did not increase the initial velocity of linoleic acid or linoleyl-CoA desaturation; (7) preincubation of microsomes with ATP also increased the 6-desaturation of oleic acid and α-linolenic acid but did not increase the 9-desaturation of plamitic and stearic acid.
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References
Brenner, R.R., and R.O. Peluffo, Biochim. Biophys. Acta 176: 471 (1969).
Brenner, R.R., Lipids 6: 567 (1971).
Oshino, N., Y. Imai and R. Sato, Biochim. Biophys. Acta 128: 13 (1966).
Kornberg, A., and W.E. Pricer, Jr., J. Biol. Chem. 204: 329 (1953).
Stadtman, E.R., in S.P. Collowick and N.O. Kaplan, “Methods in Enzymology, Vol. 3, Academic Press, New York, 1957, p. 940.
Brenner, R.R., and R.O. Peluffo, J. Biol. Chem. 241: 5213 (1966).
Lipmann, F., and L.C. Tuttle, Ibid. 193: 571 (1944).
Creasey, W.A., Biochim. Biophys. Acta 64: 559 (1962).
Pande, S.V., and J.F. Mead, J. Biol. Chem. 243: 352 (1968).
Bar-Tana, J., and B. Shapiro, Biochem. J. 93: 533 (1964).
Rossi, C.R., and D.M. Gibson, J. Biol. Chem. 239: 1694 (1964).
Dallner, G., Acta Physiol. Microb. Scand., 166 Supplementum (1963).
Marinetti, G.V., in M. Florkin and E.H. Stotz, “Comprehensive Biochemistry”, Vol. 18, Elsevier Publishing Co., Amsterdam, 1970, p. 117.
Siekevitz, P., and V.R. Potter, J. Biol. Chem. 215: 237 (1955).
Heldt, H.W., Biochem. Z. 337: 397 (1963).
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Brenner, R.R., Catala, A. Effect of ATP on the microsomal desaturation of unsaturated fatty acids. Lipids 6, 873–881 (1971). https://doi.org/10.1007/BF02531168
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DOI: https://doi.org/10.1007/BF02531168