Positional specificity in the incorporation of isomeric cis- and trans-octadecenoic acids into glycerolipids of cultured soya cells |
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Authors: | Nikolaus Weber Ingolf Richter Helmut K Mangold Kumar D Mukherjee |
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Institution: | (1) Institut für Biochemie und Technologie, H.P. Kaufmann Institut der Bundesanstalt für Fettforschung, Piusallee 68, D-4400 Münster, Federal Republic of Germany;(2) Present address: Institut für Experimentelle Pathologie, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-6900 Heidelberg, Federal Republic of Germany |
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Abstract: | Heterotrophically grown cell suspension cultures of soya (Glycine max L.) were incubated with two different mixed substrates consisting of positional isomers of either cis-1-14C]octadecenoic acids (8 to 15) or trans-1-14C]octadecenoic acids (8 to 16), each with known composition. With both substrates, about one-fourth of the radioactivity supplied was incorporated into the diacylglycerophosphocholines, while another one-fourth of the radioactivity was almost equally distributed between diacylglycerophos-phoethanolamines and triacylglycerols. All the positional isomers of cis-and trans-octadecenoic acids supplied to the cells were readily incorporated into various classes of glycerolipids. None of the octadecenoic acids was isomerized, elongated or desaturated during incubation. From the cis-octadecenoic acids, only the naturally occurring 9-isomer (oleic acid) was preferentially incorporated into position 2 of diacylglycerophosphocholines, diacylglycerophospho-ethanolamines, and triacyglycerols; all the other isomers exhibited a strong affinity for position 1 of the glycerophospholipids and positions 1 and 3 of the triacylglycerols. From the trans-octadecenoic acids, only the 9-isomer (elaidic acid) was preferentially incorporated into position 2 of diacylglycerophospho-cholines and triacylglycerols; all the other isomers preferred position 1 and positions 1 and 3, respectively, of these lipids. In diacylglycerophospho-ethanolamines, however, each of the trans-octadecenoic acids, including the 9-isomer, exhibited a strong affinity for position 1. Apparently, the enzymes involved in the incorporation of exogenous monounsaturated fatty acids into membrane lipids of plant cells can recognize the preferred substrate in a mixture of closely related isomers. |
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Keywords: | Cell cultures Glycerophospholipids Glycine Lipid metabolism Octadeeenoic acid isomers |
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