Unraveling the Reaction between Heme (FeIV=O) Moiety and H2S

血红蛋白(Hb)和肌红蛋白(Mb)与过氧化氢(H2O2)发生过氧化反应生成 卟啉/r-阳离子自由基铁化合物I(Fe‘v=O Por*+)和铁基化合物II(FeLV=O Por)，它们是 非常活泼，对红细胞有害。同时，进入血液的硫化氢(H2S) 溪流，通过环境暴露或细菌感染，可以与这些物种相互作用，导致 形成硫化血红蛋白(SulHb)和硫化肌红蛋白(SulMb)，并随后破坏Hb和 MB函数。这些失活的蛋白质，其特定的血红素中间体和反应机制仍在研究中 未知，由原血红素IX氯衍生物表征，在620 nm处有吸收带 区域，含有饱和的4-乙烯基团，其中H_2S共价键合在 吡咯“C”。我们的最新数据表明，在相同的实验条件下，在H202和H2S中， 果胶绿藻的血红蛋白I、II和III(分别为Hb1和Hbl1/Hbl11)不形成这些 亚硫胺的衍生物。HBL提供硫化氢，而HBLL和HBLL将02输送到共生菌，尽管 L在功能和化学结构上的多样性未检测到亚硫化蛋白衍生物 果胶文蛤。这种歧视是不被理解的，并将被用作理解 由于硫化血红蛋白和硫化血红素/硫化血红素的形成应通过 与过氧化氢和硫化氢反应产生的相同高价血红素中间体如下： 硫化氢 [HbL(FeM)或HbL(Fe“-O2)]+H_2O_2~-*(Fe‘V=O_2O~+)+(FeLV=O_Por)&gt；硫酸盐Hbl(A) 化合物I化合物II O2 Hbl和Mb之间的另一个显著区别是铁基化合物I接近1000倍 前者比后者更稳定。因此，我们的假设表明，硫化血红蛋白的机制 形成可能取决于(1)围绕血红素中心的氨基酸环境，(2) 铁基物种(化合物I和II)的寿命，以及(3)外围的取向和结构 血红素取代基。为了探索这些替代方案，我们将监视648 nm、620 nm和419 nm处的波段 Hbl化合物I、磺化Hb1和化合物II分别通过UV-Vis和停流的NM特性， 根据血红蛋白(Mb、Hbl、Hbl突变体和Hbl1/Hblll)的反应(A)。中级和期末 结构将通过共振拉曼光谱、核磁共振和X射线光谱分析来确定。数据将允许 关于(I)化合物I和II在人硫化Hb和硫化Mb形成中的作用，(II)解开 H_2S对吡咯“C”反应的选择性，以及(Iii)有助于直接策略的发展 用于硫化Hb或硫化Mb的处理及其对生物活性人Hb和Mb的可逆性。

The peroxidative reactions of hemoglobin (Hb) and myoglobin (Mb) with hydrogen peroxide (H2O2) produce porphyrin /r-cation radical ferryl compound I (Fe'v=O Por*+) and ferryl compound II (Felv=O Por), which are very reactive and detrimental to red cells. At the same time, hydrogen sulfide (H2S) entering the blood stream, by environmental exposure or bacterial infections, can interact with these species leading to the formation of sulfhemoglobin (sulfHb) and sulfmyoglobin (sulfMb) with the subsequent disruption of Hb and Mb function. These inactive proteins, whose specific heme intermediates and reaction mechanism are still unknown, are characterized by a protoheme IX chlorin derivative with an absorption band at the 620 nm region, bearing the saturated 4-vinyl group with a H2S covalently bound across the¿-¿ double bond of the pyrrole "C". Our latest data show that under the same experimental conditions, of H202 and H2S, the hemoglobins I, II and III, (Hbl and Hbll/Hblll, respectively), from Lucina pectinata do not form these sulfheme derivatives. Hbl delivers H2S, while Hbll and Hblll transport 02 to symbiotic bacteria, despite the diversity in function and chemical structure no sulfheme-proteins derivatives have been detected in the L pectinata clam. This discrimination is not understood and will be used as a model to comprehend the mechanism toward sulfHb and sulfMb since the formation sulfHbl and sulfHbll/sulfHblll should proceed via the same high valent heme intermediates generated by the reaction with H2O2and H2S according to: H2S [Hbl (Fem) or Hbl (Fe"-O2) ] + H2O2~-* (Fe'v=O Por¿+) + (Felv=O Por) > SulfHbl (A) Compound I Compound II O2 Other notable difference between Hbl and Mb is that the ferryl compound I is near one thousand times more stable in the former than in the latter. Thus, our hypothesis suggests that the mechanism of sulfhemeprotein formation may depends on (1) the amino acid environment surrounding the heme center, (2) the life time of the ferryl species (compound I and II), and (3) the orientation and structure of the peripheral heme substituents. To explore these alternatives, we will monitor the bands at 648 nm, 620 nm, and 419 nm characteristic of Hbl compound I, sulfHbl, and compound II, respectively, by UV-Vis and stopped flow, upon the reaction (A) of hemeproteins (Mb, Hbl, Hbl mutants, and Hbll/Hblll). The intermediate and final structures will be pursued by resonance Raman, NMR and X-ray spectroscopy. The data will allow commenting on (i) the role of compound I and II in the formation of human sulfHb and sulfMb, (ii) unravel the selectivity of H2S for the pyrrole "C" reaction , and (iii) contribute to the development of direct strategies for the treatment and reversibility of sulfHb or sulfMb to the biological active human Hb and Mb.