Vibrational relaxation of NO stretching modes in ferrous NO and ferric NO in model heme

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• 作者：Jaeheung Park ; Taegon Lee ; Manho Lim
• 关键词：Femtosecond vibrational spectroscopy ; NO bound heme protein ; Thermal relaxation ; Vibrational relaxation of NO ; Geminate rebinding ; Photodeligation of NO bound heme protein
• 刊名：Chemical Physics
• 出版年：2013
• 出版时间：30 August, 2013
• 年：2013
• 卷：422
• 期：Complete
• 页码：107-114
• 全文大小：697 K

文摘

Femtosecond IR-pump-IR-probe spectroscopy was used to measure the vibrational lifetimes (T₁) of NO stretching modes of ferrous NO near 1600 cm^?1 and ferric NO near 1900 cm^?1 at room temperature. The T₁ of NO bound to the heme, ranging from 3.5 to 34 ps, is much shorter in ferrous NO. The vibrational relaxation (VR) of NO was independent of solvent used and excess imidazole concentration, suggesting that intramolecular VR into the internal vibrational modes of the probed molecule may be the dominant pathway for VR of the bound NO. With estimated T₁ of the bound NO, we simulated transient spectra of NO bound to ferrous hemoglobin (Hb^II) after photodeligation of Hb^IINO and discussed the influence of the hot band on the determination of the dynamics of geminate rebinding of NO to Hb^II using the change in the magnitude of the fundamental band.