IRON DEPOSITION AND MOBILIZATION IN FERRITIN

从微生物到人类，铁蛋白在 铁的生物管理。在细胞内，铁是可逆的 以水合氧化铁矿物核的形式储存在铁蛋白中 在蛋白质内部。铁蛋白由两种类型的24个亚基组成，H 表观分子量21,000和19,000的重分子(重)和L(轻) G/摩尔，分别组装成分子量为C.A.的壳层。 48万克/摩尔。这两个亚基被认为具有不同的 在促进铁蛋白核心形成中的作用。一个铁氧合酶部位 它催化分子氧对铁(II)的氧化 最近在H亚基上被发现。该计划的总体目标 拟议的研究是为了阐明 铁蛋白获取和释放铁，特别注意 H和L亚基在这些过程中的作用。这些机制将是 通过EPR、Endor、ESEEM和穆斯堡尔的组合进行调查 马和羊的光谱、电化学和动力学研究 脾铁蛋白以及重组H和L人肝铁蛋白和 其定点突变体。各种EPR可观察到的铁和 在铁沉积的初始阶段形成的自由基物种将 被光谱和运动学表征以及它们的位置 在使用突变蛋白确定的蛋白质结构内 富含精选的全氢氨基酸的蛋白质。角色(S)，如果 在铁氧化和/或还原中或在 将检测对蛋白质的氧化损伤。铁的动力学 氧化和水解将通过氧电极血氧测定仪和 PH统计，并确定了这些过程的速率定律。 中间体单核和双核形成的时序 铁和自由基物种将通过快速冷冻-淬火EPR建立 光谱学。H和L亚基在促铁作用中的作用 将通过开展以下工作来探索氧化和核心形核 观察到的中间物种的光谱和动力学研究 各种定点突变体。生物还原剂与金属离子的结合 铁蛋白与铁核氧化还原化学的可逆性 将通过电化学方法进行研究。建议的广泛研究应 导致对铁蛋白如何作为一种 可逆铁储存蛋白和进一步了解 中国铁生物矿化过程的化学和生物化学 将军。

From microorganisms to man, ferritin plays a central role in the biological management of iron. Within the cell, iron is reversibly stored in ferritin in the form of a hydrous ferric oxide mineral core inside the protein. Ferritin consists of 24 subunits of two types, H (heavy) and L (light) of apparent molecular weights 21,000 and 19,000 g/mole, respectively, assembled to form a shell of molecular weight c.a. 480,000 g/mol. The two subunits have been suggested to have different roles in facilitating core formation in ferritin. A ferroxidase site which catalyzes the oxidation of iron(II) by molecular oxygen has recently been discovered on the H-subunit. The overall goal of the proposed research is to elucidate the molecular mechanisms by which ferritin acquires and releases iron with special attention paid to the roles of the H and L subunits in these processes. The mechanisms will be investigated through a combination of EPR, ENDOR, ESEEM and Mossbauer spectroscopy, electrochemistry and kinetic studies of horse and sheep spleen ferritins as well as recombinant H and L human liver ferritins and site-directed mutants thereof. The various EPR observable iron and radical species formed during the initial stages of iron deposition will be characterized spectroscopically and kinetically and their locations within the protein structure determined using mutant proteins and proteins enriched in selected perdeutero amino acids. The role(s), if any, of the observed radicals, in iron oxidation and/or reduction or in oxidative damage to the protein will be examined. The kinetics of iron oxidation and hydrolysis will be studied by oxygen electrode oximetry and pH stat, respectively, and the rate laws for these processes determined. The time sequence of formation of intermediate mononuclear and binuclear iron and radical species will be established by rapid freeze-quench EPR spectroscopy. The functions of H and L subunits in facilitating iron oxidation and core nucleation will be probed by carrying out spectroscopic and kinetic studies of intermediate species observed with various site-directed mutants. The binding of biological reductants to ferritin and the reversibility of the redox chemistry of the iron core will be studied electrochemically. The extensive studies proposed should lead to a detailed understanding of how ferritin functions as a reversible iron storage protein and further our knowledge of the chemistry and biochemistry of iron biomineralization processes in general.