The 80th JSAP Autumn Meeting 2019

Presentation information

Oral presentation

1 Interdisciplinary Physics and Related Areas of Science and Technology » 1.1 Interdisciplinary and General Physics

[18p-C206-1~8] 1.1 Interdisciplinary and General Physics

Wed. Sep 18, 2019 1:15 PM - 3:15 PM C206 (C206)

Makoto Omodani(Tokai Univ.), Hiroshi Murotani(Tokai Univ.)

1:45 PM - 2:00 PM

[18p-C206-3] Effect of Spin Degree of Freedom on the Reaction of O2 with Hemoglobin

Daiichi Kurokawa1, Jessiel Siaron Gueriba1,2, 〇Wilson Agerico Tan Dino1,3 (1.AP Osaka Univ., 2.Phys. DLSU, 3.CAMT Osaka Univ.)

Keywords:oxygen, spin degree of freedom, hemoglobin

Here, we report results of our study on the mechanism of spin-dependent O2 reaction with hemoglobin. O2 reaction with hemoglobin, which we represent as FePIm (Fe = iron, P = porphyrin, Im = imidazole), involves the transition between two spin-dependent states, viz., the oxyhemoglobin state and the deoxyhemoglobin state. The deoxyhemoglobin state pertains to FePIm and a free O2, while the oxyhemoglobin state pertains to an O2 bound to FePIm. The deoxyhemoglobin and oxyhemoglobin systems have triplet and singlet total magnetizations, respectively. We found that a spin transition from triplet to quintet to singlet mediates the O2 binding process, and this accelerates the reaction. We also found that the position of the Fe atom out of the porphyrin plane is an important indicator of O2 affinity. These results indicate that spin transitions/crossings affect the activation energy barrier. Further details will be discussed at the meeting.