Putrescine labeled, synthesis

Another novel approach to labelling molecules with carbon-11 has been published by Somawardhana, Sajjad and Lambrecht . These workers have absorbed one of the reactants required for the synthesis on a solid support and the reaction has been done by adding the other reagents to the solid support and heating the mixture in a sealed vial. One example illustrating their methodology is the formation of [l- C]putrescine. The H CN is trapped on a potassium-hydroxide-coated silica gel. Then, acrylonitrile is added, and the reaction tube sealed at both ends. After the tube had been heated at 75 °C for 5 minutes, the Michael addition product was eluted from the solid support and the solvent evaporated. Finally, the nitrile groups were reduced with a borane-dimethylsulphide complex in THF (equation 77). The total reaction time was less than 40 minutes and the product was obtained in a 53% radiochemical yield. 

Khan, H. A. and D. J. Robins, Pyrrolizidine alkaloid biosynthesis. Synthesis of C-labelled putrescines and their incorporation into retronecine, J. Chem. Soc., Perkin Trans. I, 101-105 (1985a). 

Kabalka, G. W., Wang, Z., Green, J. F., Goodman, M. M. 1992. Synthesis of isomerically pure nitrogen-13 labeled gamma-aminobutyric acid and putrescine. App. Radiat. Isot. 43 389-391. 

Figure 9.11 The formation of two examples of the tetraponerines from ants. Glutamic acid, ornithine and y-aminobutyric acid uniformly labelled with 0, sodium acetate labelled in C-1 and C-2 with Q and [l,4- C]putrescine were all used to show the synthesis is as shown...

This scant information about aminopropyltransferases is due in part to the difficulty of measuring their activities, since one of the precursors, dSAM, is unstable and not easily available. Although its synthesis has been improved, an extinction coefficient has not been published (Samejima et al., 1978). We have developed a method for the evaluation of spermidine synthase in oat leaves (Tiburcio et al., 1986a) by a coupled reaction without using dSAM. We add SAM, [ ] putrescine, and pyridoxal phosphate to the assay mixture. Incorporation of the label into spermidine can be detected after 45 min of incubation at 37 C. Labeled spermidine is separated from labeled putrescine or spermine by elution with HCl in Dowex 50 W-H" " columns (Tiburcio et al., 1986a). A similar procedure can be used for the evaluation of spermine synthase (A. F. Tiburcio et al., unpublished observations). 

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