Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
Arch Biochem Biophys. 2023 Oct 1;747:109742. doi: 10.1016/j.abb.2023.109742. Epub 2023 Sep 9.
Polyunsaturated fatty acids (PUFAs) have been extensively studied for their health benefits because they can be oxidized by lipoxygenases to form bioactive oxylipins. In this study, we investigated the impact of double bond placement on the kinetic properties and product profiles of human platelet 12-lipoxygenase (h12-LOX), human reticulocyte 15-lipoxygenase-1 (h15-LOX-1), and human endothelial 15-lipoxygenase-2 (h15-LOX-2) by using 22-carbon (C22) fatty acid substrates with differing double bond content. With respect to k/K values, the loss of Δ and Δ led to an 18-fold loss of kinetic activity for h12-LOX, no change in kinetic capability for h15-LOX-1, but a 24-fold loss for h15-LOX-2 for both C22-FAs. With respect to the product profiles, h12-LOX produced mainly 14-oxylipins. For h15-LOX-1, the 14-oxylipin production increased with the loss of either Δ and Δ, however, the 17-oxylipin became the major species upon loss of both Δ and Δ. h15-LOX-2 produced mostly the 17-oxylipin products throughout the fatty acid series. This study also investigated the effects of various 17-oxylipins on platelet activation. The results revealed that both 17(S)-hydroxy-4Z,7Z,10Z,13Z,15E,19Z-DHA (17-HDHA) and 17-hydroxy-4Z,7Z,10Z,13Z,15E-DPAn6 (17-HDPAn6) demonstrated anti-aggregation properties with thrombin or collagen stimulation. 17-hydroxy-7Z,10Z,13Z,15E,19Z-DPAn3 (17-HDPAn3) exhibited agonistic properties, and 17-hydroxy-7Z,10Z,13Z,15E-DTA (17-HDTA) showed biphasic effects, inhibiting collagen-induced aggregation at lower concentrationsbut promoting aggregation at higher concentrations. Both 17-hydroxy-13Z,15E,19Z-DTrA (17-HDTrA), and 17-hydroxy-13Z,15E-DDiA (17-HDDiA) induced platelet aggregation. In summary, the number and placement of the double bonds affect platelet activation, with the general trend being that more double bonds generally inhibit aggregation, while less double bonds promote aggregation. These findings provide insights into the potential role of specific fatty acids and their metabolizing LOX isozymes with respect to cardiovascular health.
多不饱和脂肪酸（PUFAs）因其具有健康益处而被广泛研究，因为它们可以被脂氧合酶氧化形成生物活性的氧化脂质。在这项研究中，我们通过使用具有不同双键含量的二十二碳（C22）脂肪酸底物，研究了双键位置对人血小板 12-脂氧合酶（h12-LOX）、人网织红细胞 15-脂氧合酶-1（h15-LOX-1）和人内皮 15-脂氧合酶-2（h15-LOX-2）的动力学特性和产物谱的影响。就 k/K 值而言，Δ 和 Δ 的缺失导致 h12-LOX 的动力学活性损失 18 倍，h15-LOX-1 的动力学能力没有变化，但 h15-LOX-2 的动力学活性损失 24 倍，这两种情况均适用于 C22-FAs。就产物谱而言，h12-LOX 主要产生 14-氧化脂质。对于 h15-LOX-1，随着 Δ 和 Δ 的缺失，14-氧化脂质的产生增加，但是，当 Δ 和 Δ 都缺失时，17-氧化脂质成为主要产物。h15-LOX-2 在整个脂肪酸系列中主要产生 17-氧化脂质产物。本研究还研究了各种 17-氧化脂质对血小板激活的影响。结果表明，17(S)-羟基-4Z,7Z,10Z,13Z,15E,19Z-二十二碳六烯酸（17-HDHA）和 17-羟基-4Z,7Z,10Z,13Z,15E-二十二碳四烯酸（17-HDPAn6）（17-HDPAn6）在凝血酶或胶原刺激下均表现出抗聚集特性。17-羟基-7Z,10Z,13Z,15E,19Z-二十二碳四烯酸（17-HDPAn3）表现出激动剂特性，而 17-羟基-7Z,10Z,13Z,15E-DTA（17-HDTA）表现出双相作用，在较低浓度下抑制胶原诱导的聚集，但在较高浓度下促进聚集。17-羟基-13Z,15E,19Z-二十二碳四烯酸（17-HDTrA）和 17-羟基-13Z,15E-二十二碳二烯酸（17-HDDiA）均诱导血小板聚集。总之，双键的数量和位置会影响血小板的激活，一般来说，双键越多通常会抑制聚集，而双键越少则会促进聚集。这些发现为特定脂肪酸及其代谢脂氧合酶同工酶与心血管健康之间的潜在作用提供了新的认识。
