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Effect of lipids, in particular cholesteryl 14-methylhexadecanoate, on the incorporation of labelled amino acids into transfer ribonucleic acid in vitro.

ABSTRACT: 1. Rat liver pH5 enzymes and cell sap extracted with various organic solvents showed a variable decreased incorporation of labelled amino acids into s-RNA (;soluble' or transfer RNA) in vitro. 2. The original enzymic activity could be fully restored, though at different rates, by the addition of lipid extracts in quantities corresponding to those originally present. 3. Of the main lipid groups separated from the extract, only free cholesterol and cholesteryl esters were able to reactivate the extracted pH5 enzymes in the same way as the whole lipid extract. 4. Addition of pure cholesteryl 14-methylhexadecanoate also fully restored the enzymic activity. 5. There was no energy-dependent incorporation of labelled amino acids into ribosomal protein in the presence of extracted cell sap. Addition of cholesteryl 14-methylhexadecanoate fully restored the activity of the cell sap to incorporate labelled leucine and lysine into ribosomal protein and enhanced the incorporation of labelled protein hydrolysate and phenylalanine over the level found with the corresponding non-extracted preparations. 6. It is concluded that lipids play an important role in the synthesis of aminoacyl-s-RNA complexes and that cholesteryl 14-methylhexadecanoate may be the active lipid in this respect.

SUBMITTER: Hradec J

PROVIDER: S-EPMC1187102 | biostudies-other | 1968 Nov

REPOSITORIES: biostudies-other

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Effect of cholesteryl 14-methylhexadecanoate on the activity of some amino acid-transfer ribonucleic acid ligases from mammalian tissues.

Project description:1. l-Tyrosine-, l-alanine-, l-tryptophan- and l-threonine-tRNA ligases (where tRNA is transfer RNA) were purified from mammalian tissues and the relative contents of cholesteryl 14-methylhexadecanoate were determined in fractions obtained during the isolation. Purified enzymes were extracted with various organic solvents. 2. Cholesteryl 14-methylhexadecanoate contents in purified ligases were up to 210-fold that in the starting material. Different enzymes showed different contents of this cholesteryl ester. 3. Extracted enzymes lost in most cases their ability to catalyse formation of the aminoacylhydroxamate and aminoacyl-tRNA complexes. Enzymes extracted with various solvents showed a variable decreased activity. 4. The original activity could be restored to 70-100% by the addition of cholesteryl 14-methylhexadecanoate. Cholesteryl palmitate, cholesteryl margarate and cholesteryl stearate were inactive in this respect. 5. Incubation mixtures of extracted enzymes with cholesteryl 14-methylhexadecanoate added showed an initial delay in the time-course of both reactions assayed. 6. It is concluded that the effect of cholesteryl 14-methylhexadecanoate on the activity of amino acid-tRNA ligases seems to be specific and that this compound may play some role in the function of these enzymes.

| S-EPMC1185228 | biostudies-other

Intermediate reactions in the binding of aminoacyl-transfer ribonucleic acid to rat liver ribosomes. the interaction of cholesteryl 14-methylhexadecanoate.

Project description:1. Transferase I from rat liver extracted with iso-octane binds significantly less aminoacyl-tRNA than the non-extracted enzyme. The original activity can be fully restored by the addition of cholesteryl 14-methylhexadecanoate. The binding capacity for GTP is not affected by the extraction. 2. In the presence of extracted transferase I the binding of aminoacyl-tRNA to ribosomes is decreased to 11-26% and the simultaneous binding of GTP to 32-43%. Cholesteryl 14-methylhexadecanoate induces a full reactivation of the extracted enzyme in both respects. 3. Extracted complexes A (aminoacyl-tRNA-GTP-transferase I) become bound to ribosomes to the same extent as the corresponding non-extracted preparations. 4. It is concluded that cholesteryl 14-methylhexadecanoate interacts with the binding site of transferase I for aminoacyl-tRNA and secondarily with that for GTP. It does not affect the binding site for ribosomes.

| S-EPMC1178546 | biostudies-other

The role of cholesteryl 14-methylhexadecanoate in peptide elongation reactions.

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Protein synthesis in the liver of rats injected with cholesteryl 14-methylhexadecanoate.

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Incorporation of labelled precursors into the electrophoretic fractions of rat-liver ribonucleic acid.

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| S-EPMC1218172 | biostudies-other

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