Ultraviolet difference spectroscopy of myoglobin: assignment of pK values of tyrosyl phenolic groups and the stability of the ferryl derivatives.
Ultraviolet difference spectroscopy of myoglobin: assignment of pK values of tyrosyl phenolic groups and the stability of the ferryl derivatives.
复制标题
肌红蛋白的紫外差光谱：酪氨酰酚基的 pK 值分配和 Ferryl 衍生物的稳定性。
DOI：
10.1021/bi00510a045
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发表时间：
1981
期刊：
影响因子：
2.9
通讯作者：
Peisach,J
中科院分区：
文献类型：
--
作者：
Uyeda,M;Peisach,J
M. Uyeda* 和J. Peisach* 摘要：用pH差光谱法在245 nm处研究了红袋鼠、马和抹香鲸肌红蛋白中酪氨酰酚基的电离。由于这些蛋白质中酪氨酰残基的数量分别从一到三个单调变化，因此我们能够对所有蛋白质进行pK分配。酪氨酸-146（所有肌红蛋白中的不变残基）的表观pK异常高，为12.7-12.9，因为该残基位于分子的疏水区，并且酪氨酰酚基与异亮氨酸-99的肽羰基氢键合。对于氰化铁和各种肌红蛋白的氧化形式，这种表观pX升高约0.5个pH单位，而在脱氧蛋白中，它没有显著变化。第二个酪氨酸位于103位，存在于马和抹香鲸蛋白中，但不存在于袋鼠蛋白中。在所有研究的衍生物中，其表观pK显著低于Tyr-146。第三个酪氨酰残基位于151位，是抹香鲸蛋白质所独有的，其表观pK为10.3，几乎等于酪氨酸在水溶液中的pK。三种铁基形式的表观PAT
M. Uyeda* and J. Peisach* abstract: The ionization of tyrosyl phenolic groups of ferric myoglobins from red kangaroo, horse, and sperm whale has been studied by pH difference spectroscopy at 245 nm. As the number of tyrosyl residues in these proteins varies mon-otonically from one to three, respectively, we are able to make pK assignments for all of them. The apparent pK for tyro-sine-146, an invariant residue in all myoglobins, is unusually high, 12.7-12.9, as this residue is in a hydrophobic region of the molecule and the tyrosyl phenolic group is hydrogen bonded to the peptide carbonyl of isoleucine-99. For the ferric cyanide and the oxy forms of the various myoglobins, this apparent pX is elevated by about 0.5 pH unit while in the deoxy proteins, it does not change significantly. A second tyrosine, at position 103, is found in the horse and sperm whale proteins, but not in the kangaroo protein. It has a significantly lower apparent pK than is observed for Tyr-146 in all the derivatives studied. A third tyrosyl residue, at position 151, is exclusive to the sperm whale protein and has an apparent pK of 10.3, almost equivalent to thatof tyrosine in aqueous solution. The apparent pATs for the ferryl forms of the three