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Lucina pectinata oxyhemoglobin (II-III) heterodimer pH susceptibility.
Journal of Inorganic Biochemistry ( IF 3.9 ) Pub Date : 2020-03-07 , DOI: 10.1016/j.jinorgbio.2020.111055
Darya Marchany-Rivera 1 , Clyde A Smith 2 , Josiris D Rodriguez-Perez 1 , Juan López-Garriga 1
Affiliation  

Lucina pectinata live in high concentrations of hydrogen sulfide (H2S) and contains one hemoglobin, Hemoglobin I (HbI), transporting H2S and two hemoglobins, Hemoglobin II (HbII) and Hemoglobin (HbIII), transferring dioxygen to symbionts. HbII and HbIII contain B10 tyrosine (Tyr) and E7 glutamine (Gln) in the heme pocket generating an efficient hydrogen bonding network with the (HbII-HbIII)-O2 species, leading to very low ligand dissociation rates. The results indicate that the oxy-hemeprotein is susceptible to pH from 4 to 9, at acidic conditions, and as a function of the potassium ferricyanide concentration, 100% of the met-aquo derivative is produced. Without a strong oxidant, pH 5 generates a small concentration of the met-aquo complex. The process is accelerated by the presence of salts, as indicated by the crystallization structures and UV-Vis spectra. The results suggest that acidic pH generates conformational changes associated with B10 and E7 heme pocket amino acids, weakening the (HbII-HbIII)-O2 hydrogen bond network. The observation is supported by X-ray crystallography, since at pH 4 and 5, the heme-Fe tends to oxidize, while at pH 7, the oxy-heterodimer is present. Conformational changes also are observed at higher pH by the presence of a 605 nm transition associated with the iron heme-Tyr interaction. Therefore, pH is one crucial factor regulating the (HbII-HbIII)-O2 complex hydrogen-bonding network. Thus, it can be proposed that the hydrogen bonding adjustments between the heme bound O2 and the Tyr and Gln amino acids contribute to oxygen dissociation from the (HbII-HbIII)-O2 system.

中文翻译:

露西藻(Lucina pectinata)氧合血红蛋白(II-III)异二聚体pH敏感性。

露西娜果蝇生活在高浓度的硫化氢(H2S)中,并包含一种血红蛋白,即血红蛋白I(HbI),可转运H2S和两种血红蛋白,即血红蛋白II(HbII)和血红蛋白(HbIII),可将双氧转移至共生体。HbII和HbIII在血红素囊袋中包含B10酪氨酸(Tyr)和E7谷氨酰胺(Gln),与(HbII-HbIII)-O2物种产生有效的氢键网络,导致配体解离速率非常低。结果表明,该氧血红蛋白在酸性条件下的pH值敏感于4到9,并且作为铁氰化钾浓度的函数,生成了100%的甲基水合衍生物。在没有强氧化剂的情况下,pH 5会生成一小部分浓度的水-甲基络合物。盐的存在促进了这一过程,如结晶结构和UV-Vis光谱所示。结果表明,酸性pH值会产生与B10和E7血红素口袋氨基酸相关的构象变化,从而削弱(HbII-HbIII)-O2氢键网络。该观察得到X射线晶体学的支持,因为在pH 4和5下,血红素-Fe趋于氧化,而在pH 7下,存在氧-异二聚体。由于存在与铁血红素-Tyr相互作用相关的605 nm跃迁,在较高的pH值下也观察到构象变化。因此,pH是调节(HbII-HbIII)-O2复杂氢键网络的关键因素。因此,可以提出血红素结合的O 2与Tyr和Gln氨基酸之间的氢键调节有助于从(HbII-HbIII)-O 2系统解离氧。结果表明,酸性pH值会产生与B10和E7血红素口袋氨基酸相关的构象变化,从而削弱(HbII-HbIII)-O2氢键网络。该观察得到X射线晶体学的支持,因为在pH 4和5下,血红素-Fe趋于氧化,而在pH 7下,存在氧-异二聚体。由于存在与铁血红素-Tyr相互作用相关的605 nm跃迁,在较高的pH值下也观察到构象变化。因此,pH是调节(HbII-HbIII)-O2复杂氢键网络的关键因素。因此,可以提出血红素结合的O 2与Tyr和Gln氨基酸之间的氢键调节有助于从(HbII-HbIII)-O 2系统解离氧。结果表明,酸性pH值会产生与B10和E7血红素口袋氨基酸相关的构象变化,从而削弱(HbII-HbIII)-O2氢键网络。该观察得到X射线晶体学的支持,因为在pH 4和5下,血红素-Fe趋于氧化,而在pH 7下,存在氧-异二聚体。由于存在与铁血红素-Tyr相互作用相关的605 nm跃迁,在较高的pH值下也观察到构象变化。因此,pH是调节(HbII-HbIII)-O2复杂氢键网络的关键因素。因此,可以提出血红素结合的O 2与Tyr和Gln氨基酸之间的氢键调节有助于从(HbII-HbIII)-O 2系统解离氧。削弱(HbII-HbIII)-O2氢键网络。该观察得到X射线晶体学的支持,因为在pH 4和5下,血红素-Fe趋于氧化,而在pH 7下,存在氧-异二聚体。由于存在与铁血红素-Tyr相互作用相关的605 nm跃迁,在较高的pH值下也观察到构象变化。因此,pH是调节(HbII-HbIII)-O2复杂氢键网络的关键因素。因此,可以提出血红素结合的O 2与Tyr和Gln氨基酸之间的氢键调节有助于从(HbII-HbIII)-O 2系统解离氧。削弱(HbII-HbIII)-O2氢键网络。该观察得到X射线晶体学的支持,因为在pH 4和5下,血红素-Fe趋于氧化,而在pH 7下,存在氧-异二聚体。由于存在与铁血红素-Tyr相互作用相关的605 nm跃迁,在较高的pH值下也观察到构象变化。因此,pH是调节(HbII-HbIII)-O2复杂氢键网络的关键因素。因此,可以提出血红素结合的O 2与Tyr和Gln氨基酸之间的氢键调节有助于从(HbII-HbIII)-O 2系统解离氧。由于存在与铁血红素-Tyr相互作用相关的605 nm跃迁,在较高的pH值下也观察到构象变化。因此,pH是调节(HbII-HbIII)-O2复杂氢键网络的关键因素。因此,可以提出血红素结合的O 2与Tyr和Gln氨基酸之间的氢键调节有助于从(HbII-HbIII)-O 2系统解离氧。由于存在与铁血红素-Tyr相互作用相关的605 nm跃迁,在较高的pH值下也观察到构象变化。因此,pH是调节(HbII-HbIII)-O2复杂氢键网络的关键因素。因此,可以提出血红素结合的O 2与Tyr和Gln氨基酸之间的氢键调节有助于从(HbII-HbIII)-O 2系统解离氧。
更新日期:2020-03-09
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