Cass A E, Hill A O, Smith B E, Bannister J V, Bannister W H
Biochemistry. 1977 Jul 12;16(14):3061-6. doi: 10.1021/bi00633a003.
The 270-MHz 1H nuclear magnetic resonance spectra of the apo, copper(I)-zinc(II), and copper(II)-zinc(II) forms of bovine erythrocyte superoxide dismutase (EC 1.15.1.1) are reported, and assignments of resonances to ten amino acid residues are proposed. The data require that at least four and probably six histidine residues serve as ligands to the metals in each subunit of the enzyme, consistent with x-ray diffraction results. The remaining assigned resonances are associated with His-19, His-41, Tyr-108, and the N-terminal N-acetyl group. The imidazole C(2)H of His-41 exchanges readily at pH greater than 8. The structural implications of the effect of the paramagnetic Cu(II) in the holoenzyme on the proton relaxation times are in reasonable accord with the data from x-ray diffraction studies.
本文报道了牛红细胞超氧化物歧化酶（EC 1.15.1.1）的脱辅基、铜（I）-锌（II）和铜（II）-锌（II）形式的270兆赫1H核磁共振谱，并提出了十个氨基酸残基的共振归属。数据表明，在酶的每个亚基中，至少有四个且可能有六个组氨酸残基作为金属的配体，这与X射线衍射结果一致。其余已归属的共振与His-19、His-41、Tyr-108和N端的N-乙酰基有关。His-41的咪唑C(2)H在pH大于8时容易交换。全酶中顺磁性Cu(II)对质子弛豫时间的影响的结构意义与X射线衍射研究的数据合理一致。
