実験報告書様式（一般利用課題・成果公開利用）

MLF Experimental Report
課題番号 Project No.

提出日 Date of Report
2014/7/17
装置責任者 Name of responsible person

2014A0225

Yasuhiro Miyake

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Hydration effect on electron transfer process in cytochrome c

Muon D1

and DNA probed by muon labelling method

実施日 Date of Experiment

実験責任者名 Name of principal investigator

2014/5/17 9:00 – 2014/5/19 9:00

Yoko Sugawara
所属 Affiliation
Kitasato University
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
a) Cytocrome c (104 amino acid residues with a heme from horse heart)b) Lysozyme (129 amino acid residues form hen egg white)
Water contents of both samples were adjusted to approximately 5 % (a dry sample) and 20% (a wet sample).

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

In order to investigate a hydration effect on the electron transfer process of biosystem, we measured the SRtime spectra of the following fore samples.
1. Dried sample of cytochrome c (water content approximately 5 %)2. Wetted sample of cytochrome c (water content approximately 20 %)3. Dried sample of lysozyme (water content approximately 5 %)4. Wetted sample of lysozyme (water content approximately 20 %)Cytochrome c is one of the members of the respiratory chain, and lysozyme is selected as a reference protein
which does not participate in electron transfer system.
In order to obtain information just after a pulse radiation, we used the single pulse by removing the second
pulse arriving at 600 ns after the first pulse. The Bext dependence of the longitudinal relaxation parameter ()obtained in the fitting of the observed SR time spectrum by the Risch-Kehr function was measured in theregion from 0 G to 3000 G at 300 K – 100 K.
1

2. 実験方法及び結果（つづき） Experimental method and results (continued)
Last year, we measured longitudinal SR time spectra of the wet and dry samples of cytochrome c under thelongitudinal fields of 0 - 1.4 kG, at 300 K - 150K (Proposal No. 2013A0145). This year, we collected the data inwider magnetic field range of 0 - 3000 G using a new spectrometer. In addition, we carried out the datacollection of dry cytochrome c at 100K.
Two data sets (2013A0145 and 2014A0225) of cytochrome c were consistent, and we concluded:
1. On the basis of the zero field data (Figure 1) and the plots of Bext dependence of  which showed explicit
temperature dependence, three-dimensional electron diffusion would occur at room temperature, and it was
suppressed below 200 K in the case of the wet sample. Mobility of proteins and hydration water would be
essential to optimize the structure which promotes inter-molecular three-dimensional electron transfer.
2. Temperature dependence of the dry sample is small, and at low temperature the relaxation was slow
compared with that of the wet data (Figure 1). The efficiency of one dimensional electron diffusion would beslightly smaller than that of the wet sample.
There were differences between the time dependence spectra of cytochrome c and lysozyme, but
the precision of lysozyme data was insufficient to be analyzed quantitatively because conditioningof the new detector system had not been completed at the beam time of our experiment. We aregoing to carry out remeasurements of lysozyme.

Fig.1 Temperature dependence of the zero filed date of cytochrome c.
(a) Wet sample (water content approximately 20%)2(b) Dry sample (water content approximately 5%)