Spectroscopic properties, amino acid sequence, electron transfer kinetics, and crystal structures of the oxidized (at 1.7 Å resolution) and reduced form (at 1.8 Å resolution) of a novel plastocyanin from the fern Dryopteris crassirhizoma are presented. Kinetic studies show that the reduced form of Dryopteris plastocyanin remains redox-active at low pH, under conditions where the oxidation of the reduced form of other plastocyanins is inhibited by the protonation of a solvent-exposed active site residue, His 87 (equivalent to His 90 in Dryopteris plastocyanin). The x-ray crystal structure analysis of Dryopteris plastocyanin reveals -stacking between Phe 12 and His 90 , suggesting that the active site is uniquely protected against inactivation. Like higher plant plastocyanins, Dryopteris plastocyanin has an acidic patch, but this patch is located closer to the solvent-exposed active site His residue, and the total number of acidic residues is smaller. In the reactions of Dryopteris plastocyanin with inorganic redox reagents, the acidic patch (the "remote" site) and the hydrophobic patch surrounding His 90 (the "adjacent" site) are equally efficient for electron transfer. These results indicate the significance of the lack of protonation at the active site of Dryopteris plastocyanin, the equivalence of the two electron transfer sites in this protein, and a possibility of obtaining a novel insight into the photosynthetic electron transfer system of the first vascular plant fern, including its molecular evolutionary aspects. This is the first report on the characterization of plastocyanin and the first three-dimensional protein structure from fern plant.

Structure-based virtual screening is carried out using molecular docking programs. A number of such docking programs are currently available, and the selection of docking program is difficult without knowing the characteristics or performance of each program. In this study, the screening performances of three molecular docking programs, DOCK, AutoDock, and GOLD, were evaluated with 116 target proteins. The screening performances were validated using two novel standards, along with a traditional enrichment rate measurement. For the evaluations, each docking run was repeated 1000 times with three initial conformations of a ligand. While each docking program has some merit over the other docking programs in some aspects, DOCK showed an unexpectedly better screening performance in the enrichment rates. Finally, we made several recommendations based on the evaluation results to enhance the screening performances of the docking programs.

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In this study, we investigated the induction of apoptosis by ultrasound in the presence of the novel porphyrin derivative DCPH-P-Na(I). HL-60 cells were exposed to ultrasound for up to 3 min in the presence and absence of DCPH-P-Na(I), and the induction of apoptosis was examined by analyzing cell morphology, DNA fragmentation, and caspase-3 activity. Reactive oxygen species were measured by means of ESR and spin trapping technique. Cells treated with 8 μM DCPH-P-Na(I) and ultrasound clearly showed membrane blebbing and cell shrinkage, whereas significant morphologic changes were not observed in cells exposed to either ultrasound or DCPH-P-Na(I) alone. Also, DNA ladder formation and caspase-3 activation were observed in cells treated with both ultrasound and DCPH-P-Na(I) but not in cells treated with ultrasound or DCPH-P-Na(I) alone. In addition, the combination of DCPH-P-Na(I) and the same acoustical arrangement of ultrasound substantially enhanced nitroxide generation by the cells. Sonodynamically induced apoptosis, caspase-3 activation, and nitroxide generation were significantly suppressed by histidine. These results indicate that the combination of ultrasound and DCPH-P-Na(I) induced apoptosis in HL-60 cells. The significant reduction in sonodynamically induced apoptosis, nitroxide generation, and caspase-3 activation by histidine suggests active species such as singlet oxygen are important in the sonodynamic induction of apoptosis. These experimental results support the possibility of sonodynamic treatment for cancer using the induction of apoptosis.

The crystal structure of plastocyanin from a green alga, Ulva pertusa, has been determined at 1.6-Å resolution. At its copper site, U. pertusa plastocyanin has a distorted tetrahedral coordination geometry similar to other plastocyanins. ) bond of poplar and C. reinhardtii plastocyanins by 0.14 and 0.20 Å, respectively. As a result of structural differences, U. pertusa plastocyanin has a less distorted geometry than the other plastocyanins. Thus, the cupric geometry is finely tuned by the interactions between residues 85 and 88 and between residues 83 and 88. This result implies that the copper site is more flexible than reported formerly and that the rack mechanism would be preferable to the entatic theory. The HisMet loop may regulate the electron transfer rate within the complex between plastocyanin and cytochrome f.

These results suggest that endogenous delta2-opioid-receptor-mediated systems are involved in the regulation of anxiety-related behaviors and might play a physiologically important role in the regulation of adrenocortical activity.

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Patients with critically ischemic limbs due to maintenance hemodialysis and diabetes are increasing in number markedly in Japan. The difficulty of treating critically ischemic limbs is well recognized. Despite active medication and surgical therapy, many critically ischemic limbs are amputated. Ninety-two patients with critically ischemic limbs were treated by transplantation of autologous peripheral blood stem cells (PBSCs). The stem cells were mobilized into the peripheral blood by administration of granulocyte colony stimulating factor (G-CSF). The mobilized mononuclear cells were separated by an apheresis technique using a centrifuge. The separated mononuclear cells contained approximately 4.0 x 10(7) CD34-positive cells. The collected cell suspension was divided into aliquots of 0.5-1.0 ml and transplanted into the muscle of ischemic limbs at 50-70 transplantation points. At 1.5 months after PBSC transplantation, a strong immunostaining of CD34-positive cells and factor VIII, as well as capillary formation, was observed in the muscles into which stems cells had been transplanted. In each patient tested, the serum vascular endothelial growth factor (VEGF) level increased after stem cell transplantation; the mean VEGF level increased by 176%. Of 11 diabetic patients (DM) who were not receiving hemodialysis (HD), there were no amputees regardless of their Fontaine classification. Of 19 patients in the HD(+)DM(-) category, there were no amputations in Fontaine stage I, II, and III patients, whereas three limbs and one toe were amputated in Fontaine stage IV patients. Of 13 patients in the HD(-)DM(+) category, none of the Fontaine stage I, II, or III patients underwent amputation, but six Fontaine stage IV patients underwent amputation. Of 49 patients in the HD(+)DM(+) category, 38 (78%) were classified as Fontaine stage IV, 71% (27/38) of whom had a toe or a limb amputated. In nine patients over 80 years of age, one toe and one limb were amputated. Nondiabetic, nondialyzed patients with ischemic limbs are strongly indicated for stem cell transplantation regardless of Fontaine classification. Therapeutic angiogenesis is effective for critically ischemic limbs resulting from hemodialysis and diabetes until Fontaine stage III, but is of limited effectiveness for stage IV cases.