Observations of coherent reaction dynamics in heme proteins

Femtosecond laser pulses, resonant with the Soret band of the nitric oxide complex of myoglobin (MbNO), were used to probe coherent, low-frequency nuclear motion of the heme group after photolysis. Distinct oscillations with periods of 430 and 150 femtoseconds were observed and are attributed to hem...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1994-10, Vol.266 (5185), p.629-632
Main Authors: LEYUN ZHU, SAGE, J. T, CHAMPION, P. M
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Hemoproteins
Ligand binding (Biochemistry)
Metalloproteins
Proteins
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Summary:Femtosecond laser pulses, resonant with the Soret band of the nitric oxide complex of myoglobin (MbNO), were used to probe coherent, low-frequency nuclear motion of the heme group after photolysis. Distinct oscillations with periods of 430 and 150 femtoseconds were observed and are attributed to heme doming and iron-histidine motion, respectively. These results verify that the nuclear motion of the heme is strongly coupled to the ligand binding reaction and demonstrate that such motion is not determined by overdamped (diffusive) dynamics. The relative phases and frequencies of the nuclear motion of the photoproduct suggest that the coherence arises from impulsive electronic forces associated with the spin-state change of the heme iron atom and the depopulation of its d,2 orbital during the bond-breaking event.
ISSN:0036-8075
1095-9203