Mössbauer spectroscopic investigations of photodissociated myoglobin-CO at low temperatures.
Mössbauer spectroscopic investigations of photodissociated myoglobin-CO at low temperatures.
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低温下光解肌红蛋白-CO 的穆斯堡尔光谱研究。
DOI：
10.1111/j.1432-1033.1979.tb13020.x
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
A. Trautwein
中科院分区：
文献类型：
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作者：
H. E. Marcolin;R. Reschke;A. Trautwein
肌红蛋白- co （MbCO）在低温下被光解离。光产物Mb*经穆斯堡尔光谱鉴定为铁离子高自旋配合物，其穆斯堡尔参数与脱氧肌红蛋白不同。从5 K时Mb*穆斯堡尔谱线宽在8 h时间间隔内的随时间变化可知，存在几种具有不同复合特征的Mb*构象。为了方便地获得复合行为的时间分辨率，我们研究了在恒速度穆斯堡尔驱动下，光解离后102-5·104 s时间间隔内Mb*吸收的时间依赖性。然后用各种近似步骤对所得的重组数据进行分析。结果表明，在两个独立指数的基础上解释实验数据，可以得到A1= 10s−1和A2= 105±5·102s−1数量级的指数前频率因子。在能量分布的基础上解释实验数据的尝试似乎更合理，并且与几个略有不同的Mb*构象的存在一致。相应的频率因子A约为4 s−1，因此与Austin等人在光解离后10−6 ~ 103 s的时间间隔内从光学复合数据中得到的A约为107 s−1的值不一致。复合过程的典型活化能Mb*+ CO MbCO为8 kJ/mol。低温下（T < 46 K）的复合行为可以用量子力学隧道效应来解释。
Myoglobin-CO (MbCO) has been photodissociated at low temperatures. The photoproduct Mb* has been identified by Mossbauer spectroscopy as a ferrous high-spin complex with Mossbauer parameters which are different from those of deoxy-myoglobin. From the time-dependent change of the linewidth of the Mb* Mossbauer spectrum at 5 K over a time interval of 8 h, we conclude that there exist several slightly different Mb* conformations with different recombination characteristics. In order to obtain a convenient time resolution of the recombination behavior, we have investigated the time-dependence of the Mb* absorption within a time interval of 102–5 · 104 s after the photo-dissociation, with a Mossbauer drive of constant velocity. The resulting recombination data have then been analyzed with various approximation steps. It is shown that the interpretation of experimental data on the basis of two independent exponentials leads to pre-exponential frequency factors which are of the order of A1= 10s−1 and A2= 105± 5 · 102s−1. The attempt to interpret the experimental data on the basis of a distribution of energies seems more plausible and is in agreement with the existence of several slightly different Mb* conformations. The corresponding frequency factor A is about 4 s−1 and is therefore in disagreement with the value of A (of about 107 s−1) which was derived from optical recombination data by Austin et al. within a time interval of 10−6–103 s after the photodissociation. Typical activation energies for the recombination process Mb*+ CO MbCO are 8 kJ/mol. At low temperatures (T < 46 K) the recombination behavior is explained by quantum mechanical tunnelling.