Institute for Microbial and Biochemical Sciences, USDA Forest Products Laboratory, One Gifford Pinchot Dr., Madison, WI 53726, USA.
Enzyme Microb Technol. 2011 Jun 10;49(1):25-9. doi: 10.1016/j.enzmictec.2011.04.009. Epub 2011 Apr 21.
The peroxidation of C18 unsaturated fatty acids by fungal manganese peroxidase (MnP)/Mn(II) and by chelated Mn(III) was studied with application of three different methods: by monitoring oxygen consumption, by measuring conjugated dienes and by thiobarbituric acid-reactive substances (TBARS) formation. All tested polyunsaturated fatty acids (PUFAs) were oxidized by MnP in the presence of Mn(II) ions but the rate of their oxidation was not directly related to degree of their unsaturation. As it has been shown by monitoring oxygen consumption and conjugated dienes formation the linoleic acid was the most easily oxidizable fatty acid for MnP/Mn(II) and chelated Mn(III). However, when the lipid peroxidation (LPO) activity was monitored by TBARS formation the linolenic acid gave the highest results. High accumulation of TBARS was also recorded during peroxidation of linoleic acid initiated by MnP/Mn(II). Action of Mn(III)-tartrate on the PUFAs mimics action of MnP in the presence of Mn(II) indicating that Mn(III) ions are involved in LPO initiation. Although in our experiments Mn(III) tartrate gave faster than MnP/Mn(II) initial oxidation of the unsaturated fatty acids with consumption of O(2) and formation of conjugated dienes the process was not productive and did not support further development of LPO. The higher effectiveness of MnP/Mn(II)-initiated LPO system depends on the turnover of manganese provided by MnP. It is proposed that the oxygen consumption assay is the best express method for evaluation of MnP- and Mn(III)-initiated peroxidation of C18 unsaturated fatty acids.
真菌锰过氧化物酶（MnP）/Mn（II）和螯合 Mn（III）对 C18 不饱和脂肪酸的过氧化作用研究应用了三种不同的方法：通过监测耗氧量、测量共轭二烯和测定硫代巴比妥酸反应物质（TBARS）的形成。所有测试的多不饱和脂肪酸（PUFA）在 Mn（II）离子存在下都被 MnP 氧化，但它们的氧化速率与不饱和程度没有直接关系。通过监测耗氧量和共轭二烯的形成表明，亚油酸是 MnP/Mn（II）和螯合 Mn（III）最易氧化的脂肪酸。然而，当通过 TBARS 形成监测脂质过氧化（LPO）活性时，亚麻酸产生的结果最高。在 MnP/Mn（II）引发的亚油酸过氧化过程中，也记录到 TBARS 的高积累。Mn（III）-酒石酸盐对 PUFAs 的作用模拟了 Mn（II）存在下 MnP 的作用，表明 Mn（III）离子参与 LPO 的引发。虽然在我们的实验中，Mn（III）酒石酸盐比 MnP/Mn（II）更快地引发不饱和脂肪酸的初始氧化，消耗 O（2）并形成共轭二烯，但该过程没有生产力，也不能支持 LPO 的进一步发展。MnP/Mn（II）引发的 LPO 系统的更高效率取决于 MnP 提供的锰的周转率。建议耗氧量测定是评估 MnP 和 Mn（III）引发的 C18 不饱和脂肪酸过氧化的最佳表达方法。
