Photoexcitation dynamics of azide ion bound ferric myoglobin probed by femtosecond infrared spectroscopy

IF 1.7 4区 化学
Seongchul Park, Jooyoung Kim, Manho Lim
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Abstract

The photoexcitation dynamics of N3-bound ferric myoglobin (MbN3) were investigated after exciting MbN3 in D2O at 283 K with a 575 nm pulse by probing the anti-symmetric stretching mode of the azide. Global fitting of the overall time-resolved spectra revealed that thermal relaxation of two stretching bands proceeded with a time constant of 6 ps, and that a new absorption band formed and decayed with time constants of 0.6 and 23 ps, respectively. The new absorption near 2040 cm−1 was attributed to the high-spin species 2.4 kJ/mol above the low-spin species, as the excited low-spin relaxes thermally via the high-spin species. However, this absorption could also arise from deligated N3̄ remaining within the protein. The decay of this absorption can be interpreted as either spin transition of the high-spin species into the low-spin species or geminate recombination of the dissociated N3̄. The implications of both interpretations are discussed.

Abstract Image

飞秒红外光谱探测叠氮离子结合铁肌红蛋白的光激发动力学
通过探测叠氮化物的反对称拉伸模式,研究了N3−结合的铁肌红蛋白(MbN3)在283 K的D2O中以575 nm的脉冲激发MbN3后的光激发动力学。对总时间分辨光谱的全局拟合表明,两个拉伸带的热弛豫时间常数为6 ps,新的吸收带形成和衰减时间常数分别为0.6和23 ps。在2040 cm−1附近的新吸收归因于高自旋物质比低自旋物质高2.4 kJ/mol,因为激发的低自旋物质通过高自旋物质热弛豫。然而,这种吸收也可能来自于蛋白质内部的委托N3。这种吸收的衰减可以解释为高自旋物质向低自旋物质的自旋跃迁或解离的N3的双相重组。讨论了这两种解释的含义。
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来源期刊
Bulletin of the Korean Chemical Society
Bulletin of the Korean Chemical Society Chemistry-General Chemistry
自引率
23.50%
发文量
182
期刊介绍: The Bulletin of the Korean Chemical Society is an official research journal of the Korean Chemical Society. It was founded in 1980 and reaches out to the chemical community worldwide. It is strictly peer-reviewed and welcomes Accounts, Communications, Articles, and Notes written in English. The scope of the journal covers all major areas of chemistry: analytical chemistry, electrochemistry, industrial chemistry, inorganic chemistry, life-science chemistry, macromolecular chemistry, organic synthesis, non-synthetic organic chemistry, physical chemistry, and materials chemistry.
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