SPring-8/SACLA Research Report

　We investigated in prediabetic rats the effect of creatine kinase inhibition on myosin mass transfer to actin filaments in the in situ heart with SR small-angle X-ray scattering. We established a role for ADP in increasing myosin S1 head proximity to actin filaments during diastole but suggest elevated ADP does not contribute to impaired cardiac muscle relaxation in the early stage of prediabetes.

View full abstract

　Constructing superlattices consisting of both 3d and 5d transition metal oxides is a feasible strategy to combine both strong spin-orbit coupling and magnetism in a single material. These materials are promising to be applied in future spintronic devices, magnetic sensors, etc. Here, we investigate the magnetic ordering and oxygen octahedral rotation in LaMnO₃/SrIrO₃ perovskite superlattice with strong spin-orbit coupling. Resonant magnetic
x-ray diffraction results reveal that the LaMnO₃/SrIrO₃ superlattice does not show in-plane antiferromagnetic ordering as other perovskite iridates, which may be attributed to the interfacial coupling between Mn 3d and Ir 5d orbitals. The investigation of non-resonant half-integer diffraction peaks indicate a similar oxygen octahedral rotation pattern as previous reports.

View full abstract

Show abstractHide abstract

　Metalloenzymes use the environment around the metal site to manage substrate interactions with the metal in order to effect efficient and specific catalysis under ambient conditions. Use of fs X-ray pulses from an XFEL allows to follow such reactions at room temperature (RT) without inherent radiation damage to the active site during the X-ray measurement [1-3]. We developed an approach employing simultaneous X-ray crystallography (XRD) and X-ray Emission (XES) techniques using fs XFEL-pulses [4,5] that provides complementary information: detailed information about changes in the electronic structure of the catalytic metal (XES), and the geometric changes of the metal site and the entire protein (XRD). In this experiment we used fs XFELs-pulses for RT studies of redox active metalloenzymes to capture reaction intermediates and expand time resolved studies of proteins at XFELs beyond photo-activated systems to chemically triggered systems. The main objective of this beam time was to test a novel sample delivery setup that was designed to allow drop on demand sample delivery combined with oxygen gas incubation of the individual sample drops prior to X-ray probing. We intended to test a new geometry, drop-on-wheel, which differs from our previously established drop-on-tape setup [6] and promises easier installation and operation. We included several important metalloenzymes, (ribonucleotide reductase, hydrogenase and methane monooxygenase) in this experiment to test this approach. Initial results from these tests are reported here.

View full abstract

Download PDF (2421K)

Register with J-STAGE for free!