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首页> 外文期刊>Biochemistry >ACTIVE SITE STRUCTURE IN CYTOCHROME C PEROXIDASE AND MYOGLOBIN MUTANTS - EFFECTS OF ALTERED HYDROGEN BONDING TO THE PROXIMAL HISTIDINE
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ACTIVE SITE STRUCTURE IN CYTOCHROME C PEROXIDASE AND MYOGLOBIN MUTANTS - EFFECTS OF ALTERED HYDROGEN BONDING TO THE PROXIMAL HISTIDINE

机译：细胞色素C过氧化物酶和肌球蛋白突变体的活性位点结构-氢键联结对前组氨酸的影响。

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摘要

The globins and peroxidases, while performing completely different chemistry, share features of the iron heme active site: a protoporphyrin IX prosthetic group is linked to the protein by the proximal histidine residue, X-ray absorption spectroscopy provides a method to determine the local structure of iron heme active sites in proteins, Our previous studies using X-ray absorption spectroscopy revealed a significant difference in the Fe-N-epsilon bond length between the peroxidases and the globins [for a review, see Powers, L, (1994) Molecular Electronics and Molecular Electronic Devices, Vol. 3, p 211 CRC Press Inc., Boca Raton, FL]. Globins typically have an Fe-N-epsilon distance close to 2.1 Angstrom while the Fe-N-epsilon distance in the peroxidases is closer to 1.9 Angstrom. We have proposed [Sinclair, R,, Powers, L,, Bumpus. J,, Albo, A., & Brock, B. (1992) Biochemistry 31, 4892] that strong hydrogen bonding to the proximal histidine is responsible for the shorter bond length in the peroxidases. Here we use site-specific mutagenesis to eliminate the strong proximal hydrogen bonding in cytochrome c peroxidase and to introduce strong proximal hydrogen bonding in myoglobin. Consistent with our hypothesis, elimination of the Asp235-His175 hydrogen bond in CcP results in elongation of Fe-N-epsilon from similar to 1.9 to similar to 2.1 Angstrom. Conversely, introduction of a similar strong proximal hydrogen bond in myoglobin shortens Fe-N-epsilon from similar to 2.1 to similar to 1.9 Angstrom. These results correlate well with other biochemical data.
机译：球蛋白和过氧化物酶虽然具有完全不同的化学性质，但具有铁血红素活性位点的特征：原卟啉IX修复基团通过近端组氨酸残基与蛋白质连接，X射线吸收光谱法提供了一种确定血红蛋白局部结构的方法。蛋白质中的铁血红素活性位点，我们先前使用X射线吸收光谱的研究表明，过氧化物酶和球蛋白之间的Fe-N-ε键长存在显着差异[综述，请参阅Powers，L，（1994）Molecular Electronics和分子电子设备，卷。 3，第211页CRC Press Inc.，佛罗里达州博卡拉顿]。球蛋白通常具有接近2.1埃的Fe-N-ε距离，而过氧化物酶中的Fe-N-ε距离更接近1.9埃。我们提出了[Sinclair，R，Powers，L，Bumpus。 J.，Albo，A。，＆Brock，B。（1992）Biochemistry 31，4892]认为与近端组氨酸的强氢键是过氧化物酶中键长度较短的原因。在这里，我们使用位点特异性诱变消除细胞色素c过氧化物酶中的强近端氢键，并在肌红蛋白中引入强近端氢键。与我们的假设相一致，CcP中Asp235-His175氢键的消除导致Fe-N-ε的伸长从近似1.9延伸至近似2.1埃。相反，在肌红蛋白中引入相似的强近端氢键可将Fe-N-ε的相似度从2.1缩短至1.9埃。这些结果与其他生化数据很好地相关。

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