Iron sulfide, succinate dehydrogenase

Iron-eopper coupling, cytochrome c oxidase, 326-327, 338-343 Iron sulfide, succinate dehydrogenase, 230-232, 235, 243, 244, 245, 246, 253, 254, 296... 

NADH dehydrogenase and succinate dehydrogenase also contain Fe atoms that are bound by the S atoms of cysteine residues of the protein, in association with additional, inorganic sulfide atoms. Structures of these complexes are shown in figure 10.19. Succinate dehydrogenase has three iron-sulfur centers, one with a [2Fe-2S] cluster, one with [4Fe-4S], and one with a cluster containing 3 Fe atoms and 3 (or possibly 4) sulfides. Iron-sulfur centers undergo one-electron oxidation-reduction reactions. 

Since treatment of succinate dehydrogenase with SDS for gel electrophoresis destroys the iron-sulfur chromophore and results in the loss of labile sulfide, a technique was devised by Davis and Hatefi (141-143)... 

The subunits separated by the above technique indicated a distribution of iron and labile sulfide as shown in Table X. Thus the larger subunit contained flavin, iron, and labile sulfide in the approximate ratio of 1 4 4, while the smaller subunit appeared to have the characteristics of a soluble iron-sulfur protein. The absorption spectra of succinate dehydrogenase and its two subunits analyzed to show the contributions of flavin and the iron-sulfur chromophore in each preparation are given in Fig. 27. 

Baginsky and Hatefi (155, 156) showed that loss of reconstitution activity appears to be related to a damage in the iron-sulfur system of the enzyme which is not detectable by assay for iron and labile sulfide content. They obtained a preparation of succinate dehydrogenase from complex II which exhibited no reconstitution activity but had an iron labile sulfide flavin ratio close to 8 8 1. They were then able to reactivate this enzyme for reconstitution by treating it with NajS, ferrous ions, and mercaptoethanol, essentially in the same manner as apoferredoxin had been previously converted to ferredoxin (181, 18Z). The reactivated preparation was able to reconstitute with alkali-treated submitochondrial particles or complex II. Analyses showed that the preparation had acquired additional iron and labile sulfide, but control experiments indicated that reconstitution activity was not a spurious effect. The reactiva-... 

The succinate dehydrogenase of S. acidocaldarius (DSM 639) is located in the cytoplasmic and membrane fractions when cells are disrupted either by sonication or decompressive disruption. About 10-30% of the activity is associated with the membrane fraction [30]. The purified membrane-bound succinate dehydrogenase activity (M, 141 000) consists of four subunits (Mr 66000, 31 000, 28 000, and 12,800). The enzyme contains a covalently-bound flavin as well as iron and acid-labile sulfide but no cytochrome [111]. The dehydrogenase reduces the following acceptors (listed in order of decreasing... 

Succinate dehydrogenase, like aconitase, is an iron—sulfur protein. Indeed, succinate dehydrogenase contains three different kinds of iron—sulfur clusters, 2Fe-2S (two iron atoms bonded to two inorganic sulfides), 3Fe-4S, and 4Fe-4S. Succinate dehydrogenase— which consists of two subunits, one 70 kd and the other 27 kd—differs from other enzymes in the citric acid cycle in being embedded in the inner mitochondrial membrane. In fact, succinate dehydrogenase is directly associated with the electron-transport chain, the link between the citric acid cycle and ATP formation. FADH2 produced by the... 

The early isolation and characterization of reconstitutively active succinate dehydrogenase showed that the enzyme molecule contains 8 atoms of nonheme iron and 8 atoms of acid labile sulfide per flavin (Keilin and King, 1958 King, 1963 Davis and Hatefi, 1971 Coles et al, 1972 Zanelti et al, 1972). The iron-sulfur center responsible for the g = 1.94 signal and the free radical signal due to the flavin characterize the enzyme (Beinert and Sands, 1960 King et al, 1961 DerVartanian et al, 1969). 

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