Cornelius P A, Steele A W, Chernoff D A, Hochstrasser R M
Proc Natl Acad Sci U S A. 1981 Dec;78(12):7526-9. doi: 10.1073/pnas.78.12.7526.
Picosecond transient absorption spectra of Mb, MbCO, and MbO2 have been studied at time delays of up to 10 ns after excitation at 353 nm. Particular attention has been paid to the rapid spectral changes that occur in the Soret region during the first 50 ps in MbCO and MbO2. In MbCO both the bleaching of the Soret peak (feature I) and the appearance of new deoxy-like absorption (feature II) occur instantaneously, whereas in MbO2 feature II is delayed with respect to feature I. A short-lived (approximately 12 ps) feature near 455 nm (feature III) was much more intense in MbO2 than in MbCO and was also identified in the transient spectrum of Mb. No evidence of subnanosecond geminate recombination was found in either MbCO or MbO2. These observations are consistent with a scheme in which MbO2 photodissociates through an excited state of Mb, whereas MbCO under the same conditions produces ground state Mb directly. The results and conclusions are compared with those of previous picosecond studies on these molecules and related hemoglobin derivatives.
已对肌红蛋白（Mb）、一氧化碳肌红蛋白（MbCO）和氧合肌红蛋白（MbO₂）在353 nm激发后长达10 ns的时间延迟下的皮秒瞬态吸收光谱进行了研究。特别关注了MbCO和MbO₂在最初50 ps内索雷特区域发生的快速光谱变化。在MbCO中，索雷特峰的漂白（特征I）和新的脱氧样吸收的出现（特征II）瞬间发生，而在MbO₂中，特征II相对于特征I有延迟。在455 nm附近的一个短寿命（约12 ps）特征（特征III）在MbO₂中比在MbCO中要强得多，并且也在Mb的瞬态光谱中被识别出来。在MbCO或MbO₂中均未发现亚纳秒级的双分子复合迹象。这些观察结果与一种机制相符，即MbO₂通过Mb的激发态进行光解离，而MbCO在相同条件下直接产生基态Mb。将这些结果和结论与之前对这些分子及相关血红蛋白衍生物的皮秒研究结果进行了比较。
