On 2014 Oct 20, EDWARD BERRY commented:

It is not clear that the FAD assay used here to normalize SQR and SDH activity is applicable for covalently bound FAD, such as that of SDH1p. Unless I badly misunderstand the assay, all of SDH1p flavin will go down in the perchlorate precipitation step, and they are actually measuring noncovalent FAD released by other flavoproteins (and FAD present soluble in the mitochondrial matrix). This could account for the dramatic activation upon incorporation into nanodisks and purifying by IMAC, since a lot of those proteins would not incorporate into discs. This would not invalidate the main conclusions of the paper, which are clear from the fluorescent gels, but the quantitative turnover numbers for Complex II should be taken with a grain of salt until this is cleared up

On 2014 Oct 20, EDWARD BERRY commented:

It is not clear that the FAD assay used here to normalize SQR and SDH activity is applicable for covalently bound FAD, such as that of SDH1p. Unless I badly misunderstand the assay, all of SDH1p flavin will go down in the perchlorate precipitation step, and they are actually measuring noncovalent FAD released by other flavoproteins (and FAD present soluble in the mitochondrial matrix). This could account for the dramatic activation upon incorporation into nanodisks and purifying by IMAC, since a lot of those proteins would not incorporate into discs. This would not invalidate the main conclusions of the paper, which are clear from the fluorescent gels, but the quantitative turnover numbers for Complex II should be taken with a grain of salt until this is cleared up