The positional distribution of various ∆5-acids in the seed triacylglycerols from several conifer species has been established after partial chemical degradation with Grignard reagent. The species studied were representative of four conifer families and were specially selected for their particularly high ∆5-acid contents. These species were Taxus baccata (Taxaceae; 5,9-18:2 acid, 11.9%), Larix decidua (Pinaceae; 5,9,12-18:3 acid, 28.5%), Sciadopytis verticillata (Taxodiaceae; 5,11,14-20:3 acid, 16.7%), and Juniperus communis (Cupressaceae;5,11,14,(17)(18)(19)(20) 19.8%). Calculations from the fatty acid compositions of triacylglycerols and of the mixture of 1,2-and 2,3-diacylglycerols generated by the Grignard reagent indicated that, for the four species, there was a considerable enrichment of ∆5-acids (generally more than ten times) in the 1,3-positions as compared to the 2-position, where ∆5-acids represented always less than 2% of total fatty acids esterified to triacylglycerols. This distribution was practically independent from the species (four families studied), the chainlength (18 or 20 carbon atoms), and the number of ethylenic bonds (two to four) in the ∆5-acids. Similar distributions were established for triacylglycerols from the seeds of three pine species that are available on a ton-scale: Pinus pinea, P. koraiensis, and P. pinaster. These observations confirm and extend previous studies conducted with other conifer species by similar techniques or by 13 C-nuclear magnetic resonance spectroscopy. Consequently, the almost exclusive location of ∆5-acids in the external positions of triacylglycerols is now well established and appears to be a general feature of conifer seed oils. JAOCS 74, 165-168 (1997). KEY WORDS:Conifer seed oils, ∆5-acids, positional distribution, triacylglycerols.In the search for ∆5-acids, some of which have structures closely related to those of arachidonic and eicosapentaenoic acids, and following a systematic study of conifer seed oils (1,2), four species could be selected with a high content of one of the following ∆5-acids: 5, 9-18:2, 5,9,12-18:3, 5,11,14-20:3, and 5,11,14,17-20:4 acids (double bonds in the cis configuration). These species were Taxus baccata, Larix decidua, Sciadopytis verticillata, and Juniperus communis, respectively. Moreover, each of these species is representative of one of the four conifer families, Taxaceae, Pinaceae, Taxodiaceae, and Cupressaceae, respectively. A biosynthetic pathway for these acids has recently been proposed (2), based on a ∆5-desaturase activity upon 9-18:1, 9,12-18:2, 11,14-20:2, and 11,14,17-20:3 acids as substrates.Previous 13 C-nuclear magnetic resonance (NMR) spectroscopy investigations (3,4) have shown that ∆5-acids were present in the external positions of triacylglycerols (TAG) from the seeds of all species analyzed, with apparently no ∆5-acids in the 2-position, at least within the limits of the technique (∆5-acids in amounts less than 3% could not be detected). These observations were in general agreement with those of T...
Wheat gluten was cross‐linked using water‐soluble 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide HCl (EDC). To enhance cross‐linking, N‐hydroxysuccinimide (NHS) was added to the reaction mixture. The cross‐linking efficiency was evaluated by the decrease in the amount of amino groups, the solubility of the protein in aqueous solutions with different pH levels, and by the change in the molecular weight distribution of the cross‐linked compounds. Cross‐linking was dependent on the reaction time, the molar ratio of added reactants, and the pH level of the reaction mixture. If the reaction was carried out at pH 3, no decrease in the amount of amino groups or solubility was observed. At pH 5–7, the amount of amino groups decreased from 15 to 10 mmol/100 g of protein. This was accompanied by a large decrease in the water solubility of the protein (<10%, w/v). Finally, reaction at pH 11 decreased the amount of amino groups from 15 to 8 mmol/100 g of protein. However, hardly any decrease in the water solubility was observed. Based on these results and SDS‐PAGE experiments, two cross‐link mechanisms are suggested: one resulting in inter‐ and the other resulting in intramolecular cross‐links.
No abstract
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.