Twilfer H, Gersonde K
Z Naturforsch C Biosci. 1976 Nov-Dec;31(11-12):664-74. doi: 10.1515/znc-1976-11-1207.
The electron spin resonance (ESR) spectra of 15NO- and 14NO-ligated Hb Kansas have been measured at 77 K in the range of pH 5 TO 10. At low pH the ESR spectrum is the composite of a type I and a type II spectrum which changes to another composite of type I and type II spectrum at high pH. For the definition of type I and type II spectra and the correlation of these types with two tertiary conformation states see Overkamp et al., Z. Naturforsch. 31 c, 524 [1976]. Both, the type I and the type II spectra observed at low and high pH respectively are different with regard to g-tensors and hyperfine-splitting constants. Therefore at intermediate pH values the ESR spectra of NO-Hb Kansas are the composites of four spectral components. The assignments of the four spectral components to the alpha and the beta chains are arrived at from the comparison of the ESR spectra of the alpha2Mmet beta2NO and of the alpha2MNObeta2NO species of Hb M Iwate. alpha and beta chains are both characterized by a pH-dependent spectral transition from a type I to a type II spectrum. The chains are non-equivalent with regard to both the type I and the type II spectra. The type I spectra assigned to the alpha and the beta chains are characterized by GZZ=2.0095 with a hyperfine splitting of alphaZZ(15NO)=2.36 mT and gZZ-2.0085 with a hyperfine splitting of aZZ(15NO)=2.41 mT respectively. The type II spectra assigned to the alpha and the beta chains are characterized by g*'ZZ-2.005 and a hyperfine splitting of alpha*'ZZ(15NO)-3.07 mT and g'ZZ-2.005 and a hyperfine splitting of alpha'ZZ(15NO)=3.31 mT. The change of the hyperfine splitting at gZZ during the transition from type I to type II corresponds to an increase of the spin density at the NO by about 25% in both types of chains. Comparison of type I spectra of the NO-ligated alpha and beta chains respectively demonstrates that the spin density at the NO is larger in the beta chains that in the alpha chains. The spectral types are correlated with functional states defined by the kinetics of N0-binding. Binding of inosital hexaphosphate has no influence on the ESR spectra in the whole range of pH as it is expected if NO-Hb Kandas is in the quaternary T structure.
已在77K、pH值为5至10的范围内测量了15NO-和14NO连接的堪萨斯血红蛋白（Hb Kansas）的电子自旋共振（ESR）光谱。在低pH值下，ESR光谱是I型和II型光谱的组合，在高pH值下则变为另一种I型和II型光谱的组合。关于I型和II型光谱的定义以及这些类型与两种三级构象状态的相关性，见Overkamp等人，《自然科学杂志》31c，524 [1976]。分别在低pH值和高pH值下观察到的I型和II型光谱，在g张量和超精细分裂常数方面均有所不同。因此，在中间pH值下，NO-Hb Kansas的ESR光谱是四个光谱成分的组合。通过比较Hb岩手（Hb M Iwate）的α2Mmetβ2NO和α2MNOβ2NO物种的ESR光谱，得出这四个光谱成分在α链和β链上的归属。α链和β链均具有从I型光谱到II型光谱的pH依赖性光谱转变特征。就I型和II型光谱而言，两条链是不等价的。归属于α链和β链的I型光谱的特征分别为GZZ = 2.0095，αZZ(15NO)的超精细分裂为2.36 mT；gZZ = 2.0085，αZZ(15NO)的超精细分裂为2.41 mT。归属于α链和β链的II型光谱的特征分别为g*'ZZ = 2.005，α*'ZZ(15NO)的超精细分裂为3.07 mT；g'ZZ = 2.005，α'ZZ(15NO)的超精细分裂为3.31 mT。在从I型向II型转变过程中，gZZ处超精细分裂的变化对应于两种链中NO处自旋密度增加约25%。分别比较NO连接的α链和β链的I型光谱表明，β链中NO处的自旋密度大于α链。光谱类型与由NO结合动力学定义的功能状态相关。肌醇六磷酸的结合在整个pH范围内对ESR光谱均无影响，正如预期的那样，如果NO-Hb堪萨斯处于四级T结构。
