Crepis alpina

Neff et al. (99) applied Ag-HPLC with an FID to the quantitative detection of triacylglyc-erols (TAGs) of Crepis alpina oil (CrAO). The Ag-HPLC column was a Chromsphere Lipids (4.6-mm ID X 250 mm 5 micron). All TAGs were eluted in 120 min by an isocratic mobile phase of 0.5% acetonitrile in hexane at a flow rate of 1.0 ml/min. The FID block temperature was set at 110°C, the cleaning flame hydrogen at 300 ml/min, and the oxygen flow at 175 ml/min. 

Fig. 30 Silver ion high-performance liquid chromatography (Ag-HPLC-FID) with flame ionization detector (FID) analysis of the triacylglycerols of chromatographed Crepis alpina seed oil. Ag-HPLC-FID conditions 0.5-mg sample 5-micron Chromspher Lipids column (Chrompack International, Middelburg, The Netherlands) (4.6 X 250 mm) mobile phase 0.5% acetonitrile in hexane (v/v) flow rate 1.0 ml/min FID. Chromatogram peak triacylglycerol fatty acid abbreviations S, saturated (palmitic and stearic) O, oleic L, linoleic and Cr, crepenynoic fatty acids.

Reed DW, Pohchuk DR, Buist PH, Ambrose SJ, Sasata RJ, Savile CK, Ross AR, Covello PS. Mechanistic study of an improbable reaction alkene dehydrogenation by the A12 acetylenase of Crepis alpina. J. Am. Chem. Soc. 2003 125 10635-10640. 

Crepenynic Triple bond Crepis alpina 70 A. thaliana 25 15... 

CD3 CD2I, respectively (110). Multigram quantities of methyl 12,13-dideuterioli-noleate were obtained by deuteration of methyl 18 2(9Z,12 ) (isolated from Crepis alpina) in the presence of Lindlar catalyst (111). 

Adlof, R.O., andE.A. Emken, Large-Scale Preparation of Linoleic Acid-d2-Enriched Triglycerides from Crepis alpina Seed Oil, J. Am. Oil Chem. Soc. 70 817-819(1993). 

Crepis alpina seeds have oils (triacylglycerols) where 65-80% of the fatty acids consist of crepenynic (9-octadecen-12-yonic, 18 1 A) acid. We have studied the formation of 18 1 A in developing seeds from Crepis alpina and can, for the first time, present evidence for the in-vitro activity of an acetylenic forming enzyme (acetylenase) and the partial characterization of this enzyme and its substrate. 

The ammonium salt of [ CJlinoleic (9,12 octadecadienoic, 18 2) acid was converted into radioactive ciepenynic acid (18 1 A) by detached developing cotyledons of Crepis alpina, thus demonstrating that the formation of the acetylenic bond occurs via substraction of two hydrogen atoms from a A12 double bond. 

Since the precursor fatty acid (18 2) for 18 1 A formation is likely to be formed from oleoyl-phosphatidylcholine in the E.R. (Stymne and Appelqvist, 1978), it is reasonable to assume that the acetylenase is localized outside of the plastids, and perhaps in the E.R. itself. Therefore, microsomal preparations from developing cotyledons of Crepis alpina seeds were tested for their ability to convert [ " C]18 2 into [ C] 18 1 A. Microsomes from homogenate prepared in the presence of high amount of NADH were active in converting [14C]18 2-CoA into [14C]18 1-A. 

TABLE 1. Cofactor requirement and effects of carbon monoxide, anti-cytochrome-b antibodies and KCN on A12 desaturase and A12 acetylenase activities in microsomal preparations from developing cotyledons of Crepis alpina... 

Biosynthesis of an Acetylenic Fatty Acid in Microsomal Preparations from Developing Seeds of Crepis alpina. 

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