Shulman R G, Wüthrich K, Yamane T, Antonini E, Brunori M
Proc Natl Acad Sci U S A. 1969 Jul;63(3):623-8. doi: 10.1073/pnas.63.3.623.
In proton nuclear magnetic resonance spectra of paramagnetic heme proteins, the resonances of the heme groups are shifted away from those of the many hundred protons of the polypeptide chains by interactions with the unpaired electrons and are therefore well resolved at 220 Mc. This paper describes experiments from which these resolved resonances are assigned to specific protons of the heme group in cyanoferrimyoglobin.From a comparison with the proton nuclear magnetic resonance spectra of reconstituted cyanoferrimyoglobins and the corresponding cyanoporphyrin iron (III) complexes, the following groups of heme-protons have been assigned to specific resonances in the NMR spectrum of native cyanoferrimyoglobin: the four ring methyls, the four meso protons, the two -CH groups of the vinyls, and the four methylenes of the propionate side chains. Two resonances of intensity one proton have been assigned to the proximal histidyl residue. The only heme protons whose resonances were not observed are the [unk]CH(2) groups of the vinyl groups which are probably buried in the bulk spectrum of the polypeptide chain. The present data indicate that the protein environment is more important in determining the distribution of unpaired electron density in the heme group than are the heme substituents.
在顺磁性血红素蛋白的质子核磁共振谱中，血红素基团的共振由于与未成对电子的相互作用而偏离了多肽链中数百个质子的共振，因此在220兆赫时能很好地分辨出来。本文描述了一些实验，通过这些实验将这些分辨出的共振归属于氰化高铁肌红蛋白中血红素基团的特定质子。通过与重组氰化高铁肌红蛋白和相应的氰基卟啉铁（III）配合物的质子核磁共振谱进行比较，已将以下几组血红素质子归属于天然氰化高铁肌红蛋白核磁共振谱中的特定共振：四个环甲基、四个中位质子、乙烯基的两个-CH基团以及丙酸侧链的四个亚甲基。两个强度为一个质子的共振已归属于近端组氨酸残基。唯一未观察到共振的血红素质子是乙烯基的[unk]CH(2)基团，它们可能掩埋在多肽链的整体谱中。目前的数据表明，在决定血红素基团中未成对电子密度的分布方面，蛋白质环境比血红素取代基更为重要。
