Formation of iron(III)-tyrosinate is the fastest reaction observed in ferritin.
Formation of iron(III)-tyrosinate is the fastest reaction observed in ferritin.
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DOI：
10.1021/bi00211a039
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发表时间：
1993-12
期刊：
影响因子：
2.9
通讯作者：
G. Waldo;Elizabeth C. Theil
中科院分区：
文献类型：
--
作者：
G. Waldo;Elizabeth C. Theil
铁蛋白的快速矿化，具有h型亚基的蛋白质特征，与特定铁(III)-酪氨酸复合物的形成一致。铁（II）被h -亚基型铁蛋白氧化的伪一级速率常数现在已被证明比以前报道的铁蛋白大700-900倍；x = 1000 s-1，形成特定的铁(III)-酪氨酸配合物（A550nm）或形成不太明确的铁(III)-氧多核配合物（A420nm）。多核铁(III)-氧配合物的形成和氧的消耗是双相的。在第一阶段，多达50个铁原子/铁蛋白分子被快速氧化，同时形成铁(III)-酪氨酸络合物；形成铁(III)-酪氨酸复合物的位点的饱和也需要50个铁/铁蛋白分子。通过绘制矿化快速阶段的初始氧化速率与添加的[Fe(II)]的曲线得到的s形曲线表明，铁氧化的反应途径比先前描述的更为复杂。在矿化的第二阶段，铁(III)-酪氨酸减少，但多核铁(III)-氧配合物和氧气消耗继续以较慢的速度增加。快速氧化途径的恢复与铁(III)-酪氨酸形成位点的恢复平行；铁(III)-酪氨酸位点的完全再生在12小时内是逐渐的，似乎铁（III）沿着蛋白质生物矿化途径的运动是缓慢的，并且伴随着影响铁(III)-酪氨酸位点的构象变化。（摘要删节250字）
Rapid mineralization of ferritin, characteristic of protein with H-type subunits, coincides with formation of a specific Fe(III)-tyrosinate complex. The pseudo-first-order rate constant for Fe(II) oxidation by H-subunit-type ferritin has now been shown to be 700-900 times greater than any previously reported for ferritin; kox = 1000 s-1 for formation of the specific Fe(III)-tyrosinate complex (A550nm) or formation of less defined Fe(III)-oxo multinuclear complexes (A420nm). Formation of multinuclear Fe(III)-oxo complexes and O2 consumption were biphasic. In the first phase, up to 50 Fe atoms/ferritin molecule were rapidly oxidized, accompanied by formation of the Fe(III)-tyrosinate complex; saturation of the sites which formed the Fe(III)-tyrosinate complex also required 50 Fe/ferritin molecule. The sigmoidal shape of the curve obtained by plotting the initial rate of oxidation during the rapid phase of mineralization versus added [Fe(II)] suggested a more complex reaction pathway of ferroxidation than previously described. During the second phase of mineralization, Fe(III)-tyrosinate decreased, but multinuclear Fe(III)-oxo complexes and O2 consumption continued to increase at a slower rate. Recovery of the rapid oxidation pathway paralleled recovery of the site for Fe(III)-tyrosinate formation; full regeneration of the Fe(III)-tyrosinate sites was gradual over a period of 12 h, as if the movement of Fe(III) along the biomineralization pathway in the protein was slow and was accompanied by conformational changes which affected the Fe(III)-tyrosinate site.(ABSTRACT TRUNCATED AT 250 WORDS)