The diverse inhibitors of bovine heart mitochondrial complex I (NADH-ubiquinone oxidoreductase) are believed to share a common large binding domain with partially overlapping sites, though it remains unclear how these binding sites relate to each other. To obtain new insight into the inhibitor binding domain in complex I, we synthesized a photoreactive azidoquinazoline {[(125)I]-6-azido-4-(4-iodophenethylamino)quinazoline, [(125)I]AzQ}, in which a photolabile azido group was introduced into the toxophoric quinazoline ring to allow specific cross-linking, and carried out a photoaffinity labeling study using bovine heart submitochondrial particles. Analysis of the photo-cross-linked proteins by peptide mass fingerprinting and immunoblotting revealed that [(125)I]AzQ specifically binds to the 49 kDa and ND1 subunits with a frequency of approximately 4:1. The cross-linking was completely blocked by excess amounts of other inhibitors such as acetogenin and fenpyroximate. Considerable cross-linking was also detected in the ADP/ATP carrier and 3-hydroxybutyrate dehydrogenase, though it was not associated with dysfunction of the two proteins. The partial proteolysis of the [(125)I]AzQ-labeled 49 kDa subunit by V8-protease and N-terminal sequencing of the resulting peptides revealed that the amino acid residue cross-linked by [(125)I]AzQ is within the sequence region Thr25-Glu143 (118 amino acids). Furthermore, examination of fragment patterns generated by exhaustive digestion of the [(125)I]AzQ-labeled 49 kDa subunit by V8-protease, lysylendopeptidase, or trypsin strongly suggested that the cross-linked residue is located within the region Asp41-Arg63 (23 amino acids). The present study has revealed, for the first time, the inhibitor binding site in complex I at the sub-subunit level.

We report a time-resolved propagating spin wave spectroscopy for Fe19Ni81 film. We show that the amplitude of the spin-wave packet depends on the direction of magnetization and that its phase can be controlled by the polarity of pulsed magnetic field for the excitation. The nonreciprocal emission of spin-wave packet can be utilized for the binary spin-wave input into the spin-wave logic circuit.

We measure the current and shot noise in a quantum dot in the Kondo regime to address the nonequilibrium properties of the Kondo effect. By systematically tuning the temperature and gate voltages to define the level positions in the quantum dot, we observe an enhancement of the shot noise as temperature decreases below the Kondo temperature, which indicates that the two-particle scattering process grows as the Kondo state evolves. Below the Kondo temperature, the Fano factor defined at finite temperature is found to exceed the expected value of unity from the noninteracting model, reaching 1.8±0.2.

The performance of spintronic devices critically depends on three material parameters, namely, the spin polarization in the current (P), the intrinsic Gilbert damping (α), and the coefficient of the nonadiabatic spin transfer torque (β). However, there has been no method to determine these crucial material parameters in a self-contained manner. Here we show that P, α, and β can be simultaneously determined by performing a single series of time-domain measurements of current-induced spin wave dynamics in a ferromagnetic film.