Biochemie des Peroxysoms in der Leberzelle

Sies, Helmut

doi:10.1002/ange.19740862202

Cited by 30 publications

(3 citation statements)

References 157 publications

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“…The coincidence of an absence of peroxisomes, i.e., a site of breakdown of mitochondrial H20 z [45,46], and of alterations at the site of mitochondrial H20: production, which is attributed to the succinate-cyt b region of the respiratory chain and the system of energy conservation [47,48], may not be causally related. A decreased activity of glutathione peroxidase, suggested by the decreased serum selenium level [49] in our patient, might additionally interfere with H202 metabolism without being related to the basic defect.…”

Section: Discussionmentioning

confidence: 92%

A metabolic disorder similar to Zellweger syndrome with hepatic acatalasia and absence of peroxisomes, altered content and redox state of cytochromes, and infantile cirrhosis with hemosiderosis

Versmold¹,

Bremer

Herzog

et al. 1977

Eur J Pediatr

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A patient with a cerebro-hepato-renal syndrome was investigated. The visceral manifestations were those of the Zellweger syndrome (ZS); however, the child exhibited muscular hypertonia and survived into the 2nd year of life. Ultramicroscopically, hepatocytes were lacking peroxisomes, but, contrary to findings in one patient with ZS [2], contained smooth endoplasmic reticulum. No catalase was found by histochemistry or spectroscopy. Mitochondria showed normal succinate and glutamate respiration, and normal coupling of respiration to the phosphorylation potential. The cytochrome (cyt) content was diminished to one-third with an abnormally inversed redox pattern of the respiratory chain in the controlled state, cyt b being 5%, cyt c 23% reduced. The oxygen affinity of cyt a3 was normal. These findings exclude a defect in the nonheme iron protein region of the respiratory chain as described in ZS [2], but point to a functional abnormality of cyt b in out patient.

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Section: Discussionmentioning

confidence: 92%

A metabolic disorder similar to Zellweger syndrome with hepatic acatalasia and absence of peroxisomes, altered content and redox state of cytochromes, and infantile cirrhosis with hemosiderosis

Versmold¹,

Bremer

Herzog

et al. 1977

Eur J Pediatr

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“…Zunächst fällt auf, daß die Katalase-Aktivität eine erstaunliche Konstanz aufweist. Die mittlere spezifische Aktivität liegt etwa halb so hoch wie in der Ratten-Leber (29). Der Glutathiongehalt der menschlichen Leber beträgt mit ca.…”

Section: Ergebnisse Und Diskussionunclassified

Die Aktivität des Peroxid-metabolisierenden Systems in Human-Leber

Konz¹

1979

Clinical Chemistry and Laboratory Medicine

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Zusammenfassung: Die Aktivitäten verschiedener peroxid-metabolisierender Enzyme wurden in Homogenaten vonHuman-Leberexzisionen bestimmt. Die spezifischen Aktivitäten (± Standardabweichung) der selenhaltigen bzw. der nicht-selenabhängigen Glutathionperoxidase betrugen 41,1 ± 23,7 bzw. 30,5 ± 14,0 mU/mg Protein. Katalase und Superoxiddismutase lagen in einem Gewebsgehalt von 4,72 ± 0,58 bzw. 1,87 ± 0,68 Mg/mg Protein vor. Das freie lös-liche Gesamtglutathion betrug 12,9 ± 7,4 nmol/mg Protein. Der Lipidperoxidgehalt wurde in Form von in-vitro gebildetem Malondialdehyd zu 0,32 ± 0,14 nmol/mg Protein bestimmt. Diese Enzym-bzw. Substratgehalte liegen beim Menschen erheblich tiefer als bei Ratte und Maus. Glutathiongehalt und Selenperoxidase korrelieren positiv mit r = 0,48 ±0,31. Selen-Peroxidase und Nicht-Selen-Peroxidase korrelieren negativ mit r = -0,71 ±0,18; Superoxiddismutase und Lipidperoxidgehalt korrelieren ebenfalls negativ mit r = -0,47 ± 0,3 1 . Die vorliegenden Befunde unterstreichen die zentrale Bedeutung dieser protektiven Systeme für die Integrität der Humanleber. The activity of the peroxide-metabolizing system in human liverSummary: The activities of various peroxide-metabolizing enzymes were determined in homogenates of human liver excisions. The specific activity of selenium-dependent glutathione peroxidase was 41.1 ± 23.7 (S.D.) mU/mg protein; non-selenium glutathione peroxidase showed an activity of 30.5 ± 14.0 mU/mg protein. The catalase and Superoxide dismutase concentrations were 4.72 ± 0.58 and 1.87 ± 0.68 Mg/mg protein, respectively. Total glutathione amounted to 12.9 ± 7.4 nmol/mg. Malondialdehyde formation, used as the basis for the determination of lipid hydroperoxides, was 0.32 ± 0.14 nmol/mg. The data indicate much lower enzyme and substrate levels compared to rats and mice. A positive correlation of r = 0.48 ± 0.31 was found between the glutathione level and selenium-dependent peroxidase. Selenium-dependent and non-selenium-glutathione peroxidase correlate negatively (r = -0.71 ± 0.18); Superoxide dismutase concentration and lipid-hydroperoxides are also related by a negative correlation coefficient of r = -0.47 ± 0.31. These data stress the major hepatoprotective role of these systems in human liver.

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“…Moreover, of cell-physiological interest is the observation that not only externally added organic hydroperoxides or hydrogen peroxide, but also H,O, generated within the hepatocyte may lead to a lower steady-state degree of reduction of cytochrome h,. Although a complete knowledge of the metabolic role of cytochrome h, is lacking to date, such effects may supply another physiological sense for hydroperoxide defense systems such as catalase and glutathione peroxidase (cJ recent reviews [11,121).…”

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confidence: 99%

Oxidation of Cytochrome b₅ by Hydroperoxides in Rat Liver

Sies

Grosskopf

1975

European Journal of Biochemistry

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Spectral changes following the addition of hydroperoxides to isolated hepatocytes and to perfused rat liver were observed. Cytochrome b5 is the major, if not the only, hemoprotein exhibiting redox changes under these conditions: cytochrome b5 is oxidized by added hydroperoxides, e.g. tert‐butyl or cumene hydroperoxides. No spectral changes attributable to cytochrome b5 were observed with tert‐butanol. The effect is present also when the mitochondrial respiratory chain is inhibited by antimycin A, and it is not observable with isolated mitochondria. On the other hand, the oxidation of cytochrome b5 by hydroperoxides is readily demonstrable in microsomal fractions in presence of NADH. Spectral evidence for a participation of the other microsomal hemoprotein, cytochrome P‐450, in the hydroperoxide‐linked effects was not obtained. Thus, in hepatocytes from phenobarbital‐pretreated rats, no formation of cytochrome P‐420, no displacement of a type I substrate, hexobarbital, and no major steady state redox change of cytochrome P‐450 was detectable. However, when cytochrome P‐450 was dithionite‐reduced, an oxidation of this cytochrome occurred upon subsequent hydroperoxide addition. Hydrogen peroxide addition to hepatocytes also leads to a lower steady‐state degree of reduction of cytochrome b5. Evidence is provided with hepatocytes from rats pretreated with 3‐amino‐1,2,4‐triazole that H2O2 generated intracellularly, e.g. from added glycolate, also causes a detectable oxidation of cytochrome b5. The mechanism of these hydroperoxide effects remains to be established, and it is not clear whether cytochrome b5 reacts directly or indirectly. However, it is suggested that these effects may be of significance for the further study of cytochrome‐b5‐linked metabolic pathways.

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Biochemie des Peroxysoms in der Leberzelle

Cited by 30 publications

References 157 publications

A metabolic disorder similar to Zellweger syndrome with hepatic acatalasia and absence of peroxisomes, altered content and redox state of cytochromes, and infantile cirrhosis with hemosiderosis

A metabolic disorder similar to Zellweger syndrome with hepatic acatalasia and absence of peroxisomes, altered content and redox state of cytochromes, and infantile cirrhosis with hemosiderosis

Die Aktivität des Peroxid-metabolisierenden Systems in Human-Leber

Oxidation of Cytochrome b₅ by Hydroperoxides in Rat Liver

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Biochemie des Peroxysoms in der Leberzelle

Cited by 30 publications

References 157 publications

A metabolic disorder similar to Zellweger syndrome with hepatic acatalasia and absence of peroxisomes, altered content and redox state of cytochromes, and infantile cirrhosis with hemosiderosis

A metabolic disorder similar to Zellweger syndrome with hepatic acatalasia and absence of peroxisomes, altered content and redox state of cytochromes, and infantile cirrhosis with hemosiderosis

Die Aktivität des Peroxid-metabolisierenden Systems in Human-Leber

Oxidation of Cytochrome b5 by Hydroperoxides in Rat Liver

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Oxidation of Cytochrome b₅ by Hydroperoxides in Rat Liver