Caracelli I, Meirelles N C, Tabak M, Baffa Filho O, Nascimento O R
EMBRAPA-EPEAL, Maceió, Brasil.
Biochim Biophys Acta. 1988 Aug 10;955(3):315-20. doi: 10.1016/0167-4838(88)90210-5.
The nitrosyl derivatives of Annelidae Glossoscolex paulistus hemoglobin (an earth worm erythrocruorin (Ec AGp)) and Aplysia brasiliana myoglobin (Mb Apb) are studied using ESR spectroscopy. These two proteins have a quite similar ESR spectra at 100 K, but a different temperature behaviour. The temperature dependence of the nitrosyl Mb Apb spectrum is in good agreement with the Boltzmann distribution. In the case of nitrosyl-Ec AGp, the results are explained by the existence of two types of spectrum in thermodynamic equilibrium, with delta H = 9.08 kJ/mol, delta S = 47.15 J/mol and T1/2 = 193 K. There is a great similarity of the nitrosyl-Ec AGp spectra with those reported for elephant myoglobin, suggesting the presence of the same heme environment with a glutamine residue in the distal site. The pH dependence of the spectrum of nitrosyl-Mb Apb shows that the affinity of nitrosyl binding is higher at high pH (7.3) than at low pH (4.6). The ESR parameters are the same for these two pH values.
利用电子自旋共振光谱对环节动物圣保罗舌形虫血红蛋白（一种蚯蚓红细胞血色素（Ec AGp））和巴西海兔肌红蛋白（Mb Apb）的亚硝酰基衍生物进行了研究。这两种蛋白质在100 K时具有非常相似的电子自旋共振光谱，但温度行为不同。亚硝酰基Mb Apb光谱的温度依赖性与玻尔兹曼分布吻合良好。对于亚硝酰基-Ec AGp，其结果可通过存在处于热力学平衡的两种光谱类型来解释，其中ΔH = 9.08 kJ/mol，ΔS = 47.15 J/mol且T1/2 = 193 K。亚硝酰基-Ec AGp光谱与报道的大象肌红蛋白光谱有很大相似性，表明在远端位点存在相同的血红素环境以及一个谷氨酰胺残基。亚硝酰基-Mb Apb光谱的pH依赖性表明，亚硝酰基结合亲和力在高pH（7.3）时高于低pH（4.6）时。这两个pH值下的电子自旋共振参数相同。
