scholarly journals Topological arrangement in microsomal membranes of hepatic haem oxygenase induced by cobalt chloride

1979 ◽  
Vol 178 (2) ◽  
pp. 331-337 ◽  
Author(s):  
Y Hino ◽  
H Asagami ◽  
S Minakami
Keyword(s):  
Cytochrome C ◽  
Time Course ◽  
Reductase Activity ◽  
Microsomal Preparation ◽  
Cytochrome C Reductase ◽  
Nadph Cytochrome ◽  
Oxygenase Activity ◽  
Microsomal Membranes ◽  
Haem Oxygenase ◽  
Nadph Cytochrome C Reductase

1. The microsomal haem oxygenase activity induced by the administration of CoCl2 was found mainly in the smooth-surfaced microsomal fraction, whereas that of the untreated control animals was widely distributed in smooth-surfaced microsomal, rough-surfaced microsomal and Golgi fractions. 2. When microsomal preparation was incubated and the time course of the distribution of biliverdin between the membranes and the medium was followed, most of the biliverdin formed was found first in the medium. This suggests that the active site of haem oxygenase is exposed on the cytoplasmic surface of the membranes. The possible localization of the enzyme at the outer surface of the membranes was also supported by a digestion experiment with trypsin. The haem oxygenase activity was greatly decreased even at low concentration of the proteinase, which did not affected the NADPH-cytochrome c reductase activity. 3. When microsomal preparation was further fractionated by isopycnic centrifugation in the presence of deoxycholate or by partitioning of sonicated microsomal preparation in aqueous-polymer two-phase systems, most of the haem oxygenase activity was found in a fraction different from the main fraction of the NADH- and NADPH-cytochrome c reductase and NADH–ferricyanide reductase activities. This indicates the different distribution of haem oxygenase from the other enzymes mentioned, on the lateral plane of microsomal membranes, and suggests the different localization of the haem oxygenase system from the electron-transport system linked with cytochrome b5 and cytochrome P-450.

Temperature Influence on Basal Activity and Induction of Mixed Function Oxygenase Activity in Fundulus heteroclitus

1979 ◽  
Vol 36 (11) ◽  
pp. 1400-1405 ◽  
Author(s):  
John J. Stegeman
Keyword(s):  
Cytochrome C ◽  
Fundulus Heteroclitus ◽  
Reductase Activity ◽  
Control Fish ◽  
Cytochrome C Reductase ◽  
Nadph Cytochrome ◽  
Pyrene Hydroxylase ◽  
Mixed Function Oxygenase ◽  
Cytochrome P 450 ◽  
Nadph Cytochrome C Reductase

Treatment of Fundulus heteroclitus acclimated to 6.5 °C with benzo(a)pyrene did not elicit any change in the levels of hepatic microsomal NADH- or NADPH-cytochrome c reductase activity, nor in the levels of cytochrome P-450 or its catalytic activities. However, the same treatment offish at 16 5 °C resulted in a marked induction of benzo(a)pyrene hydroxylase and NADPH-cytochrome c reductase. Cytochrome P-450 content was also higher in the warm, treated fish and the Soret maximum of reduced, CO-treated microsomes was shifted to the violet. Levels of aminopyrine demethylase and NADH-cytochrome c reductase activities did not show a significant treatment effect. At neither temperature could treated and control fish be distinguished on the basis of in vitro inhibition of benzo(a)pyrene hydroxylase activity by 7,8-benzoflavone. Levels of NADPH-cytochrome c reductase and benzo(a)pyrene hydroxylase activities were greater in control Fundulus acclimated to 6.5 °C than to 16.5 °C, when normalized to microsomal protein, but not when based on body weight. The results indicate that habitat temperature alone may not affect the capacity for initial hydrocarbon metabolism in fish, but that it can strongly influence the induction of cytochrome P-450. Key words: temperature, cytochrome P-450, hydrocarbon metabolism, mixed-function oxygenase, Fundulus heteroclitus

scholarly journals Enzymic conversion of α-oxyprotohaem IX into biliverdin IXα by haem oxygenase

1990 ◽  
Vol 270 (3) ◽  
pp. 659-664 ◽  
Author(s):  
T Yoshinaga ◽  
Y Sudo ◽  
S Sano
Keyword(s):  
Cytochrome C ◽  
Kinetic Study ◽  
Maximum Velocity ◽  
Incubation Mixture ◽  
Biliverdin Reductase ◽  
Cytochrome C Reductase ◽  
Nadph Cytochrome ◽  
Haem Oxygenase ◽  
Biliverdin Ix ◽  
Nadph Cytochrome C Reductase

Conversion of four isomers of meso-oxyprotohaem IX into the corresponding biliverdin IX was attempted with a reconstituted haem oxygenase system in the presence of NADPH-cytochrome c reductase and NADPH. Only the alpha-isomer of meso-oxyprotohaem IX was converted effectively into biliverdin IX alpha, which was further reduced to bilirubin IX alpha by biliverdin reductase. Only trace amounts of biliverdins IX beta, IX gamma and IX delta were respectively formed from the incubation mixture of the corresponding oxyprotohaemin IX isomers with the complete haem oxygenase system under the same conditions. In a kinetic study, the Km for alpha-meso-oxyprotohaem IX was 3.6 microM, which was 2-fold higher than that for protohaem IX. The maximum velocity (Vmax.) of the conversion of alpha-meso-oxyprotohaem IX into biliverdin IX alpha was twice as fast as that of protohaem IX. These results demonstrate that alpha-meso-oxyprotohaem IX is an intermediate of haem degradation and it was converted stereospecifically into biliverdin IX alpha via verdohaem IX alpha.

scholarly journals Electron-transport pathway of the NADH-dependent haem oxygenase system of rat liver microsomal fraction induced by cobalt chloride

1979 ◽  
Vol 178 (2) ◽  
pp. 323-329 ◽  
Author(s):  
Y Hino ◽  
S Minakami
Keyword(s):  
Cytochrome C ◽  
Rat Liver ◽  
Microsomal Fraction ◽  
Cytochrome B5 ◽  
Transport Pathway ◽  
Cytochrome C Reductase ◽  
Nadph Cytochrome ◽  
Haem Oxygenase ◽  
Reported Data ◽  
Nadph Cytochrome C Reductase

The hepatic microsomal haem oxygenase activity of rats treated with CoCl2 was studied kinetically by measuring biliverdin, the immediate product of the reaction. Biliverdin was extracted with diethyl ether/ethanol mixture, and was determined by the difference between A690 and A800. The apparent Km value for NADPH (at 50 microM-haematin) was about 0.2 microM when an NADPH-generating system was used, whereas that for NADH was about 630 microM. Essentially the same Vmax. values were obtained for both the NADH- and NADPH-dependent haem oxygenase reactions. No synergism was observed with NADH and NADPH. The NADH-dependent reaction was competitively inhibited by NADP+, with a Ki of about 10 microM. The inhibitoin of the NADH-dependent reaction by the antibody against rat liver microsomal NADPH-cytochrome c reductase was essentially complete, with a pattern similar to that of the NADPH-dependent reaction. The immunochemical experiment and the comparison of the kinetic values with the reported data on isolated NADH-cytochrome b5 reductase and NADPH–cytochrome c reductase indicated the involvement of the latter enzyme in NADH-dependent haem oxygenation by microsomal fraction in situ.

Biosynthesis, utilization, and translocation of endogenous isomeric spin-labelled radioactive cytidinediphosphodiglycerides from isolated guinea pig liver microsomal to mitochondrial membranes

1979 ◽  
Vol 57 (7) ◽  
pp. 1019-1025 ◽  
Author(s):  
L. Stuhne-Sekalec ◽  
N. Z. Stanacev
Keyword(s):  
Cytochrome C ◽  
Guinea Pig ◽  
Reductase Activity ◽  
Mitochondrial Membranes ◽  
Pig Liver ◽  
Cytochrome C Reductase ◽  
Lipid Species ◽  
Microsomal Membranes ◽  
Guinea Pig Liver ◽  
Nadph Cytochrome C Reductase

When isolated guinea pig liver microsomal membranes were incubated with isomeric (5-, 12-, and 16-doxyl stearoyl) spin-labelled sn-3-[2-3H]phospfaatidic acid in the presence of CTP and Mg2+, formation of corresponding CDP-[2-3H]diglycerides (in an amount representing 16.5–17.4% of the labelled lipids), which were acceptable substrates in the microsomal biosynthesis of sn-3-[2-3H]phosphatidyl-myo-[U-l4C]inositols, took place. When microsomal membranes containing known amounts of labelled CDP-diglycerides were incubated with unlabeled mitochondrial membranes, reisolated mitochondria contained labelled lipids in an amount which could not be accounted for by the microsomal contamination of reisolated mitochondria, determined by the assay of NADPH – cytochrome c reductase activity, establishing therefore the translocation of labelled CDP-diglycerides (and other labelled lipids) from microsomal to mitochondrial membranes in an amount of ~50% of microsomal content. The rate of loss of paramagnetic lipid species in microsomal and in reisolated mitochondrial membranes was found to be quite different. When reisolated mitochondria containing trans-located isomeric spin-labelled CDP-[2-3H]diglycerides were further incubated with sn-3-[U-14C]glycerophosphate, the formation of labelled phosphatidylglycerophosphate and phosphatidylglycerol was detected. These findings established that the translocation of endogenously formed CDP-[2-3H]diglycerides occurred from isolated microsomal membranes to both outer and inner mitochondrial membranes.

A chimeric iron-sulfur flavoprotein endowed with NADPH-cytochrome c reductase activity

1996 ◽  
Vol 24 (1) ◽  
pp. 22S-22S ◽  
Author(s):  
Giuliana Zanetti ◽  
Luciano Piubelli ◽  
Roberta Zucca Tanci ◽  
Alessandro Aliverti
Keyword(s):  
Cytochrome C ◽  
Reductase Activity ◽  
Cytochrome C Reductase ◽  
Nadph Cytochrome ◽  
Iron Sulfur ◽  
Nadph Cytochrome C Reductase
Sign in / Sign up

Export Citation Format

Share Document