X-ray structures of catalytic intermediates of cytochrome c oxidase provide insights into its O2 activation and unidirectional proton-pump mechanisms.

Cytochrome c oxidase (CcO) reduces O2 to water, coupled with a proton-pumping process. The structure of the O2-reduction site of CcO contains two reducing equivalents, Fe a32+ and CuB1+, and suggests that a peroxide-bound state (Fe a33+-O--O--CuB2+) rather than an O2-bound state (Fe a32+-O2) is the initial catalytic intermediate. Unexpectedly, however, resonance Raman spectroscopy results have shown that the initial intermediate is Fe a32+-O2, whereas Fe a33+-O--O--CuB2+ is undetectable. Based on X-ray structures of static noncatalytic CcO forms and mutation analyses for bovine CcO, a proton-pumping mechanism has been proposed. It involves a proton-conducting pathway (the H-pathway) comprising a tandem hydrogen-bond network and a water channel located between the N- and P-side surfaces. However, a system for unidirectional proton-transport has not been experimentally identified. Here, an essentially identical X-ray structure for the two catalytic intermediates (P and F) of bovine CcO was determined at 1.8 Šresolution. A 1.70 ŠFe-O distance of the ferryl center could best be described as Fe a34+ = O2-, not as Fe a34+-OH- The distance suggests an ∼800-cm-1 Raman stretching band. We found an interstitial water molecule that could trigger a rapid proton-coupled electron transfer from tyrosine-OH to the slowly forming Fe a33+-O--O--CuB2+ state, preventing its detection, consistent with the unexpected Raman results. The H-pathway structures of both intermediates indicated that during proton-pumping from the hydrogen-bond network to the P-side, a transmembrane helix closes the water channel connecting the N-side with the hydrogen-bond network, facilitating unidirectional proton-pumping during the P-to-F transition.

Nephrotic syndrome with portal, splenic and renal vein thrombosis. A case report.

BACKGROUND: Thromboembolism is known as a major complication of nephrotic syndrome, but only 4 cases of portal vein thrombosis have been reported as a complication of nephrotic syndrome. All of these 4 cases had acute symptoms, and 3 of 4 were in relapsing phase of nephrotic syndrome when thrombi were found. We describe here a case of 51-year-old woman with fresh nephrotic syndrome that was asymptomatically complicated by portal, splenic and renal vein thrombosis. CONCLUSIONS: In the presence of fresh nephrotic syndrome of minimal change, asymptomatic and widely distributed, including portal vein, thrombus formation occurred. If the clinical course shows resistance to therapy, we must consider the complication of venous thrombosis. Anticoagulant therapy with heparin and warfarin was effective and all thrombi disappeared without any other complications.

[Novel renal function marker, ATP--establishing the normal range, cases of anti-tumor drags administration for urinary-track tumor, diabetic diseases and a newborn baby].

Urinary free ATP assay by the firefly luciferin-luciferase method is a rapid and simple method for determining renal function, especially uriniferous tubule function. Normal range of urinary free ATP concentration, daily ATP excretion in urine, urinary ATP/creatinine value and ATP decomposition activity in urine is 1.1 x 10(-9)-3.4 x 10(-8) M, 4.0 x 10(-9)-4.1 x 10(-8) mole, 5.0 x 10(-13)-5.9 x 10(-11) mol/mgCr and 100-77% express for the remaining rate of additional ATP, respectively. A significant correlation was found between free ATP concentration and daily ATP excretion in urine with a correlation coefficient of 0.84. In cases of anti-tumor drug(cisplatin = cis-diamminedichloroplatinum II) administration for urinary-track tumor, abnormal urinary free ATP concentration and ATP decomposition activity in urine were clearly demonstrated after a few days of cisplatin administration. The appearance of a tendency toward abnormal relative ATP values were similar to changes in beta 2-MG and NAG values. Diabetic patients often demonstrate unusually high values of urinary free ATP concentration. In asphyxia of the newborn, urinary ATP/creatinine value were significantly higher than those in healthy newborn, but urinary NAG values did not differ.