Hamberg M
Department of Physiological Chemistry, Karolinska Institutet, Stockholm, Sweden.
Biochem Biophys Res Commun. 1992 Nov 16;188(3):1220-7. doi: 10.1016/0006-291x(92)91361-s.
Incubation of [1-14C]6(Z),9(Z),12(Z)-octadecatrienoic acid with an enzyme preparation from the red alga Lithothamnion corallioides Crouan led to the formation of two new compounds, i.e. the conjugated tetraene 6(Z),8(E),10(E),12(Z)-octadecatetraenoic acid and the bis-allylic hydroxy acid 11(R)-hydroxy-6(Z),9(Z),12(Z)-octadecatrienoic acid. These two compounds were formed by independent pathways and were not interconvertible by the enzyme preparation. Experiments with stereospecifically deuteriated 6,9,12-octadecatrienoic acids demonstrated that formation of 6,8,10,12-octadecatetraenoic acid was accompanied by loss of the pro-S and pro-R hydrogens from C-8 and C-11, respectively, whereas formation of 11-hydroxy-6,9,12-octadecatrienoic acid proceeded with loss of the pro-S hydrogen from C-11. Biosynthesis of 6,8,10,12-octadecatetraenoic acid was dioxygen-dependent and was accompanied by production of hydrogen peroxide. A number of artificial electron acceptors supported formation of 6,8,10,12-octadecatetraenoic acid under anaerobic conditions. The existence in Lithothamnion corallioides of a fatty acid oxidase that catalyzes the oxidation of certain poly-unsaturated fatty acids into conjugated tetraene fatty acids is postulated.
将[1-¹⁴C]6(Z),9(Z),12(Z)-十八碳三烯酸与红藻石枝藻（Lithothamnion corallioides Crouan）的酶制剂一起温育，导致形成了两种新化合物，即共轭四烯6(Z),8(E),10(E),12(Z)-十八碳四烯酸和双烯丙基羟酸11(R)-羟基-6(Z),9(Z),12(Z)-十八碳三烯酸。这两种化合物通过独立的途径形成，并且不能通过该酶制剂相互转化。用立体定向氘代的6,9,12-十八碳三烯酸进行的实验表明，6,8,10,12-十八碳四烯酸的形成分别伴随着来自C-8和C-11的前-S和前-R氢的损失，而11-羟基-6,9,12-十八碳三烯酸的形成伴随着来自C-11的前-S氢的损失。6,8,10,12-十八碳四烯酸的生物合成是双氧依赖性的，并伴随着过氧化氢的产生。许多人工电子受体在厌氧条件下支持6,8,10,12-十八碳四烯酸的形成。推测石枝藻中存在一种脂肪酸氧化酶，它催化某些多不饱和脂肪酸氧化成共轭四烯脂肪酸。
