Effect of lysine ionization on the structure and electrochemical behaviour of the Met44-->Lys mutant of the blue-copper protein azurin from Pseudomonas aeruginosa.
Effect of lysine ionization on the structure and electrochemical behaviour of the Met44-->Lys mutant of the blue-copper protein azurin from Pseudomonas aeruginosa.
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赖氨酸电离对铜绿假单胞菌蓝铜蛋白天青蛋白的 Met44-->Lys 突变体的结构和电化学行为的影响。
DOI：
10.1111/j.1432-1033.1993.tb18369.x
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Peisach,J
中科院分区：
文献类型：
--
作者：
VandeKamp,M;Canters,GW;Andrew,CR;Sanders-Loehr,J;Bender,CJ;Peisach,J
研究了赖氨酸残基取代产气假单胞菌天青蛋白疏水表面的Met 44的结构和光谱化学效应，并与赖氨酸的电离态进行了比较.在pH 5-8范围内，野生型和Met 44-→Lys（M44 K）天青蛋白的光学吸收、共振拉曼、EPR和电子自旋回波包络调制光谱性质非常相似，表明Cu-位点几何结构得到了保持。在较高的pH值下，M44 K天青蛋白（pKa 9 -10）中Lys 44的去质子化伴随着最大吸光度的变化（614 nm和450 nm，而不是625 nm和470 nm）和EPRg λ值（2.298而不是2.241），表明在高pH下Cu的键合相互作用的变化。M44 K天青蛋白的电子自交换速率的强pH依赖性支持Lys 44的归属。作为可电离基团，并证明了疏水补丁的电子转移的重要性。野生型和M44 K天青蛋白中点电位的pH依赖性可以通过His 35和His 83的电离以及突变的额外静电效应来解释。
The structural and spectrochemical effects of the replacement of Met44 in the hydrophobic surface patch of azurin fromPseudomonas aeruginosaby a lysine residue were studied as a function of the ionization state of the lysine. In the pH range 5–8, the optical absorption, resonance Raman, EPR and electron spin‐echo envelope modulation spectroscopic properties of wild‐type and Met44‐→Lys (M44K) azurin are very similar, indicating that the Cu‐site geometry has been maintained. At higher pH, the deprotonation of Lys44 in M44K azurin (pKa9–10) is accompanied by changes in the optical‐absorption maxima (614 nm and 450 nm instead of 625 nm and 470 nm) and in the EPRg∥value (2.298 instead of 2.241), indicative of a change in the bonding interactions of Cu at high pH. The strong pH dependence of the electron self‐exchange rate of M44K azurin supports the assignment of Lys44 as the ionizable group and demonstrates the importance of the hydrophobic patch for electron transfer. The pH dependence of the midpoint potentials of wild‐type and M44K azurin can be accounted for by the ionizations of His35 and His83 and by the additional electrostatic effect of the mutation.