Studies on Succinate Dehydrogenase

Abstract

Autolysates of brewer's yeast contain several isoenzymes of fumarate reductase. One group (Type I) has a molecular weight of 62,000 to 63,000, as determined by chromatography on Sephadex, and 5 components in the group have been detected and partially or completely separated on triethylaminoethyl cellulose. Another group (Type II) consists of at least 2 isoenzymes. The predominant component shows a molecular weight of 34,000 and the minor one 112,000 ± 10,000 on Sephadex. One of the Type I enzymes has been extensively purified until it shows a single component on gradient centrifugation, although it appears to be heterogeneous on polyacrylamide electrophoresis. The prosthetic group is FAD and, in addition, iron and possibly, copper appear to be present. In contrast to mitochondrial succinate dehydrogenase the FAD is not covalently bound and the non heme iron is not linked to labile sulfide. Preliminary electron paramagnetic resonance data suggest that the iron may undergo oxidation‐reduction during the catalytic cycle. The absorption spectrum manifests the 450 mμ band of flavoproteins but there is an anomalous absorption below 400 mμ and in the long wave‐length region. Dithionite and succinate bleach the 450 mμ band and fumarate partially restores the color of the enzyme.

Properties and Function of Fumarate Reductase (NADH) in Streptococcus Lactis

“…The spectrum was similar to that obtained for. the fumarate reductase from yeast (Tisdale et al 1968), and the absorbance maximum at 450 nm suggested the presence of a flavin group .. This was shown by the method of Burch (1957) to be~n:F AD molecule which was not covalently bound to the protein.…”

Purification and properties of fumarate reductase from baker's yeast.

“…In this paper, the absorption spectrum of the enzyme revealed peaks at 380 and 456nm, and shoulders at 370, 440 and 478nm. Tisdale et al,5) however, showed that the maximumof an absorption spectrum was 450 nm, and that the peak near 375nmwas obscured by overlapping with a chromophoric component. The difference in the absorption spectra between their result and ours may be due to the purity of the enzymepreparation.…”

“…The difference in the absorption spectra between their result and ours may be due to the purity of the enzymepreparation. According to Tisdale et al,5) …”

Purification and characterization of fumarate reductase from Methanobacterium thermoautotrophicum

“…Contrary to all these membrane associated fumarate reductases, there is evidence for fumarate reductase activity in the soluble fraction of the cell extracts of baker's yeast (48) and brewers yeast (49). The only similarity between the soluble and the membrane bound fumarate reductase is that they are all f1avoproteins.…”

“…On the contrary, fumarate reductases isolated from brewers yeast (65) and bakers yeast (49) were found to be in the cytosol fraction of the Reducing agents helped in protecting against loss in the enzyme activity, provided that a strict anaerobic environment was maintained. Furthermore, unlike the results Nozaki et al (66) observed, the inactivated enzyme could not be reactivated by incubation with reducing agents under anaerobic conditions.…”