X-ray powder diffraction and Raman scattering experiments for solid methane were carried out at pressures up to 37 GPa and room temperature. The diffraction pattern of phase B at 16.9 GPa is assigned to a cubic lattice with lattice constant of 7.914 Å (B. At the transition from phase B to the HP phase, the pressure-volume curve shows an anomaly without the structural change.

The effects of various formate concentrations on both the donor and the acceptor sides in oxygen-evolving PS II membranes (BBY particles) were examined. EPR, oxygen evolution and variable chlorophyll fluorescence have been observed. It was found that formate inhibits the formation of the S(2) state multiline signal concomitant with stimulation of the Q(A)(-)Fe(2+) signal at g = 1.82. The decrease and the increase in intensities of the multiline and Q(A)(-)Fe(2+) signals, respectively, had a linear relation for formate concentrations between 5 and 500 mM. The g = 4.1 signal formation measured in the absence of methanol was not inhibited by formate up to 250 mM in the buffer. In the presence of 3% methanol the g = 4.1 signal evolved as formate concentration increased. The evolved signal could be ascribed to the inhibited centers. Oxygen evolution measured in the presence of an electron acceptor, phenyl-p-benzoquinone, was also inhibited by formate proportionally to the decrease in the multiline signal intensity. The inhibition seemed to be due to a retarded electron transfer from the water-oxidizing complex to Y(Z)(+), which was observed in the decay kinetics of the Y(Z)(+) signal induced by illumination above 250 K. These results show that formate induces inhibition of water oxidation reactions as well as electron transfer on the PS II acceptor side. The inhibition effects of formate in PS II were found to be reversible, indicating no destructive effect on the reaction center induced by formate.

The pressure-induced phase transformation of solid CF 4 at room temperature was studied with x-ray and Raman scattering experiments. The space group of phase III was determined as P2 1 /c. The pressure dependences of the intramolecular vibrational modes suggest phase transitions from phase III to IV at 8.9 GPa and from phase IV to V at 13.6 GPa.

Light-induced spin-polarized radical pairs, P700'A-j in spinach photosystem (PS) I particles and P680'Qp in Zn-substituted PS II core complexes, in oriented membranes were studied by pulsed electron paramagnetic resonance (EPR). Based on the determined distance of 25.2 ± 0.2 A between P700 and A" the angular dependence of the spin-polarized electron spin echo envelope modulation (ESEEM) spectra on the magnetic field suggests that the angle between RPlop_A , the radiusvector connecting P700 and A" and the membrane normal n was 24 ± 4° in PS I particles. Obtained angle and distance of P700-A, axis suggested Q K side in the molecular geometry of cofactors presented in a recent X-ray crystallography of cyanobacterial PS I reaction center to be an active branch of electron transfer. The distance between P680 and Q A was determined to be 27.4 ± 0.3 A for a nonoriented PS II. The angle between RP680_Qp, the radius-vector connecting P680 and Q A , and n was determined to be 21 ± 5°. The angle of P680-QA axis was close to that of 20° of P870-QA axis reported in X-ray analysis of the purple bacterial reaction center crystal.