Fatty acid isotope incorporation

We must conclude from the manner in which the isotope of fatty acids is incorporated into acetoacetic acid, as well as from other lines of evidence (see Section VII), that the formation of 2-carbon fragments is a fundamental step in the oxidation of fatty acids by animal tissues. 

Problem 29.5 Evidence for the role of acetate in fatty-acid biosynthesis comes from isotope-labeling experiments. If acetate labeled with 13C in the methyl group ( CFtyCC H) were incorporated into fatty acids, at what positions in the fatty-acid chain would you expect the, 3C label to appear ... 

Scrimgeour, C. M., Begley, I. S. and Thomason, M. L. (1999) Measurement of deuterium incorporation into fatty acids by gas chromatography/isotope ratio mass spectrometry. Rapid Communications in Mass Spectrometry 13, 271. 

FIGURE 2. The pyruvate and the acetate pool are both needed for the formation of the introductory compound of plastidic Mev pathway. Isoprenoid (Car -H PQ) and fatty acid (16 0 -M8 1) formation in developing chloroplasts was stud j.ed in an isotopic dilution experiment. Chloroplasts (31 - 38 pg chi ml vol 1 ml) were supplied with the labeled precursor and increasing cunounts of jnlabeled substrate in the following combinations. Absolute values of C-incorporation j.nt(j> isoprenoids and fatty acids, in nmol C incorporated (mg chi) h -100, are indicated by brackets //. FIG. 2A 5 mM NaH CO (540 KBq)... 

---