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Y Nonaka

Publications and source records attributed to Y Nonaka.

At least 91 records · Page 5Linked to original sources
PubMed1987

Molecular cloning and sequence analysis of full-length cDNA for mRNA of adrenodoxin oxidoreductase from bovine adrenal cortex.

A full-length cDNA clone (pADR) for adrenodoxin reductase was isolated by means of immunological screening from a bovine adrenal poly(A)+ mRNA library. A cDNA insert of 1,973 base pairs in length encoded the entire amino acid sequence of the adrenodoxin reductase precursor protein, which consists of 492 amino acids including an extrapeptide of 32 amino acids at the NH2-terminus. The cloned cDNA contained the complete 3'-noncoding region of 443 nucleotides including 59 nucleotides of poly(A) and 51 nucleotides in the 5'-noncoding region. The amino acid sequences from the 33rd to 70th, the 117th to 123rd, the 207th to 225th, the 247th to 323rd, the 385th to 426th, the 444th to 461st, and the 487th to 492nd in the predicted structure were identical with those of the purified adrenodoxin reductase and its digested peptides, with only four exceptions.

Adrenal Cortex↗
PubMed1986

Effect of calmodulin on aldosterone synthesis by a cytochrome P-45011 beta-reconstituted system from bovine adrenocortical mitochondria.

Bovine adrenocortical calmodulin was purified and its general properties were examined. The latter were similar to those of bovine brain calmodulin. When added to a cytochrome P-450(11)beta-reconstituted system in the presence of dilauroylphosphatidylcholine, calmodulin decreased the rate of aldosterone production from corticosterone from 0.8 to 0.1 nmol/(min X nmol P-450), while it increased the rate of 18-hydroxycorticosterone production from 1.8 to 4.6 nmol/(min X nmol P-450). This effect of calmodulin on steroid production was maximum at a concentration of 1 microM, when 1 microM cytochrome P-450(11)beta was used. The effect was dependent on the presence of Ca2+, and maximal response was observed at less than 1 microM Ca2+. There was essentially no difference in the effect when bovine brain calmodulin was used. Calmodulin induced a change in the activity of cytochrome P-450(11)beta in the presence of a wide concentration range of corticosterone as a substrate. As for 18-hydroxycorticosterone production, calmodulin increased both the maximal activity and the apparent Km for corticosterone, but it decreased the apparent Km for adrenodoxin. Adrenodoxin at a concentration of less than 20 microM did not fully abolish the effect of calmodulin. A small type I difference spectrum appeared when calmodulin was added to cytochrome P-450(11)beta. The difference spectrum increased significantly in the presence of both Ca2+ and adrenodoxin. These results suggest that calmodulin interacts with cytochrome P-450(11)beta in the presence of adrenodoxin and then modulates the activity of aldosterone synthesis catalyzed by cytochrome P-450(11) beta.

Adrenal Cortex↗
PubMed1986

The semiquinone state of NADPH-adrenodoxin oxidoreductase in the course of anaerobic reduction with NADPH.

NADPH-adrenodoxin oxidoreductase was titrated with NADPH under anaerobic conditions. As the amount of added NADPH was increased to a ratio to the reductase of 1 : 1, a broad absorbance band from approximately 500 to 900 nm, which is attributed to a charge transfer complex, increased and then sharply decreased after the 1 : 1 ratio was attained. Concomitant with the decrease in the charge transfer band, a peak at 575 nm with a shoulder at 635 nm increased, indicating the formation of a semiquinone. This showed clearly that a semiquinone was formed only when more than the stoichiometric amount of NADPH (It is meant by "the stoichiometric amount of NADPH" that the molar ratio of NADPH to adrenodoxin reductase is equal to one, that is, NADPH/FAD bound to the reductase = 1.) was added. The semiquinone band reached its maximum with an approximately 3-fold excess of NADPH over the reductase, and then gradually decreased. Concurrent with the decrease in absorbance of both the charge transfer complex and the semiquinone, the reaction mixture was bleached, indicating that a pale colored species was produced. 1H NMR studies suggested that the pale colored species was a complex of fully reduced adrenodoxin reductase and NADPH, and that the semiquinone also bound 1 mol of the pyridine nucleotide per mol of the reductase. These data suggest that the semiquinone state of the reductase is observable only when a complex between NADPH and the enzyme in the flavin semiquinone is formed.

Anaerobiosis↗
PubMed1985

Effects of prazosin on platelet aggregation and plasma beta-thromboglobulin in essential hypertension.

Platelet aggregation in response to adenosine 5'-diphosphate (ADP) and plasma levels of beta-thromboglobulin (beta-TG) were followed in 10 subjects with essential hypertension without any manifest vascular complications and in 14 age-matched normotensive controls. The effects of prazosin on blood pressure and platelet function were also examined in the subjects with hypertension. Platelet aggregation in response to 5 microM ADP was significantly greater in the subjects with hypertension than in the controls. Plasma beta-TG levels were 30% higher in the subjects with hypertension than in the controls. The increased platelet aggregation and plasma levels of beta-TG in the subjects with hypertension returned to normal after the blood pressure had been controlled by prazosin therapy. Our data suggest that the aggregation and release reactions of platelets increase in uncomplicated essential hypertension, and that prazosin may have some beneficial effects on the prevention of vascular complications in hypertension by normalizing platelet function as well as by lowering blood pressure.

Adult↗
PubMed1985

Phosphorus-31 nuclear magnetic resonance and electronic spectroscopic studies of adrenodoxin reductase and its binary complex with NADP+.

The 31P NMR spectra of NADPH-adrenodoxin reductase and its complex with NADP+ are reported. The spectrum of adrenodoxin reductase showed two doublets arising from the phosphorus nuclei in the pyrophosphate group of FAD. Both doublets were shifted upfield to different extents in comparison with those of free FAD. Further, one of the doublets of phosphorus nuclei of the pyrophosphate group of bound NADP+ in the complex of adrenodoxin reductase and NADP+ was considerably shifted upfield in comparison with that of free NADP+. The spectrum of the complex of the reductase and NADP+ showed that the resonance of the 2'-phosphate group of NADP+ bound to the reductase was shifted downfield by 1.37 ppm compared with that of free NADP+ in the dianionic state. The 2'-phosphate resonance of bound NADP+ was independent of pH within the physiological range, whereas that of free NADP+ changed according to its ionization. The resonance of the 2'-phosphate group of NADP+ bound to the reductase also revealed that the ratio for the complex of NADP+ and the reductase was 1:1, and that this complex formation was inhibited by a high KCl concentration. These results were confirmed by electronic spectroscopic studies.

Adrenal Cortex↗
PubMed1985

Synthesis of aldosterone by a reconstituted system of cytochrome P-45011 beta from bovine adrenocortical mitochondria.

When corticosterone was incubated with cytochrome P-45011 beta purified from bovine adrenocortical mitochondria in the presence of adrenodoxin, NADPH-adrenodoxin reductase and an NADPH generating system, aldosterone as well as 18-hydroxycorticosterone were formed with turnover numbers of 0.23 and 1.1 nmol/min/nmol P-450, respectively. Phospholipids extracted from adrenocortical mitochondria remarkably enhanced the activity of aldosterone formation by the cytochrome P-45011 beta-reconstituted system. The apparent Km and turnover number were estimated to be 6.9 microM and 2.0 nmol/min/nmol P-450 for aldosterone formation in the presence of the lipidic extract. When 18-hydroxycorticosterone was tested as a substrate, cytochrome P-45011 beta showed catalytic activity for aldosterone synthesis with an apparent Km and turnover number of 325 microM and 5.3 nmol/min/nmol P-450, respectively. Carbon monoxide and metyrapone inhibited the production of aldosterone from corticosterone and that from 18-hydroxycorticosterone. These results suggest that conversion of corticosterone and of 18-hydroxycorticosterone to aldosterone occurs through P-45011 beta-catalyzed reaction.

Adrenal Cortex↗
PubMed1985

A crystallographic investigation on NADPH-adrenodoxin oxidoreductase.

Single crystals of NADPH-adrenodoxin oxidoreductase were grown in 50 mM potassium phosphate (pH 7.4) containing 5% glycerol and ammonium sulfate. The crystals are monoclinic, belong to space group P21 and have dimensions of a= 83.4 A, b = 62.6 A, c = 59.3 A, alpha = gamma = 90 degrees, and beta = 107.1 degrees. There is one molecule per asymmetric unit.

Adrenal Glands↗
PubMed1985

Differences of immunoglobulin secreting cells in bone marrow from those in circulation: relevance to their development.

The surface markers of immunoglobulin secreting cells (ISC) in bone marrow and peripheral blood were analysed. Circulating ISC bear surface Ig and Ia-like antigens. However, these markers were not detectable on ISC in bone marrow. Fc and complement receptors were not present on circulating ISC. The areas of plaques corresponding to Ig secretion by bone marrow cells were always larger than those of peripheral blood cells. Although the majority of ISC were typical plasma cells, plasmacytoid lymphocytes were observed in peripheral blood. These findings seem to indicate that ISC in the peripheral blood are less advanced in their differentiation and maturation pathway from B lymphocytes to plasma cells than those in bone marrow. ISC in mesenteric lymph nodes exhibited nearly the same phenotype as peripheral cells.

Antigens, Surface↗
PubMed1984

Clinical features and course of aortitis syndrome in Japanese women older than 40 years.

The clinical features and course of aortitis syndrome were studied in 11 women older than 40 years of age. The patients were Japanese women, mean age 57 +/- 6 years old, who were followed for 6.9 +/- 3.8 years. Data from 24 young patients were used for comparison. In the older patients, systemic hypertension (73%), calcification of the aorta (73%), left ventricular hypertrophy (92%) and cardiomegaly (82%) were frequent, whereas the erythrocyte sedimentation rate was normal in 5 patients and only slightly accelerated in 6. C-reactive protein was positive in 2. The incidence of cardiac involvement and inflammatory signs was significantly different from findings in the young patients. Aortic regurgitation (AR) (55%) was significantly more frequent and renal artery stenosis was not observed. Other arterial lesions revealed a pattern similar to those seen in the young patients. An irregular luminal surface, kinking and calcification were present in the lesions in the older patients. The survival rate at 5 years was 80%. Five of 6 patients with AR had congestive heart failure, 4 of whom died. One died after a stroke. Thus, aortitis syndrome in older patients has a long course. There is usually an associated AR, renal artery stenosis is rare and other arterial lesions do not change a great deal. The prognosis may be good, but depends on the association of AR.

Adult↗
PubMed1984

Aldosterone biosynthesis by a reconstituted cytochrome P-45011 beta system.

[3H]Corticosterone was incubated with cytochrome P-45011 beta purified to electrophoretic homogeneity from bovine adrenocortical mitochondria, and the reaction products were analyzed by high performance liquid chromatography. The production of aldosterone (21.2 pmol/nmol P-450/min) and 18-hydroxycorticosterone (1.17 nmol/nmol P-450/min) was observed. When lipidic extracts from mitochondria of bovine adrenocortical zona glomerulosa were added to the reaction mixture, the rate of production of aldosterone was increased 28-fold. When [3H]18-hydroxycorticosterone was incubated with cytochrome P-45011 beta, the amount of aldosterone produced was 55.7 pmol/nmol P-450/min in the absence of the lipidic extracts and the enhancing effect of the lipidic extracts was 4-fold.

18-Hydroxycorticosterone↗
PubMed1984

Effect of phospholipid on aldosterone biosynthesis by a cytochrome P-450(11) beta-reconstituted system.

Effect of phospholipid on aldosterone synthesis catalyzed by a cytochrome P-450(11)beta-reconstituted system was examined. Corticosterone was incubated with P-450(11)beta in the presence of phosphatidylcholine, phosphatidylethanolamine, cardiolipin, phosphatidylinositol, or phosphatidylserine. These phospholipids stimulated the rate of aldosterone- and 18-hydroxycorticosterone-synthesis, although the mode of stimulation by neutral phospholipids was different from that by acidic phospholipids. In the presence of a phospholipid mixture containing the lipids in the same molar ratios as found in adrenocortical mitochondria, the rate of production of aldosterone increased 10-fold over the rate without the lipids, and that of 18-hydroxycorticosterone increased 3-fold. The maximal synthetic rates of aldosterone and 18-hydroxycorticosterone were 2 and 5 nmol/nmol P-450/min, respectively.

18-Hydroxycorticosterone↗
PubMed1983

A prominent feature of the conversion of P-450 to P-420 of cytochrome P-450B1 among the cytochrome P-450 isozymes.

Conversion of cytochrome P-450 to P-420 was observed with the use of three isozymes of P-450, P-450PB, P-450MC and P-450B1. The last one, which was isolated and characterized in our laboratories, is the cytochrome P-450 with high affinity for cytochrome b5. Of these isozymes, cytochrome P-450B1 is predominantly fast in the rate of conversion from P-450 to P-420 in the reduced state under carbon monoxide. p-Nitroanisole, which is the substrate of P-450B1 for demethylation, accelerated the conversion, whereas the effects of the compound on the rate of conversion of the other P-450S were small. The effect of cholate on the conversion was distinct and rapid but not very selective among the isozymes. Stabilization with glycerol for prevention of the conversion was found to be effective, for any of these isozymes. No remarkable difference was observed in the stability of the oxidized state among these isozymes when detected in the CO-reduced form. The rates of the reaction from the oxidized to the CO-reduced form were measured with these isozymes. The rate of P-450B1 was the highest in both the medium with glycerol and that without glycerol. Circular dichroism was measured with respect to conversion of P-450 to P-420. The absorption at 450 nm was related to the significant circular dichroism, while the increased absorption at 420 nm due to the conversion was not accompanied by distinct circular dichroism. These data support the concept that the heme vicinity of cytochrome P-450B1 is more labile in the structure of the reduced form under carbon monoxide than those of the other isozymes.

Animals↗