NSC804515

Cytotoxicity assays are usually based on the assessment of cell membrane damage, which can also be indirectly detected by measuring cell viability. Detection methods include MTT assay, CKK-8 assay, LDH assay and ATP assay, etc.

Inclusion-body recovery uses insoluble recombinant protein aggregates from E. coli as a starting material; the workflow is cell disruption, inclusion-body isolation/washing, denaturant or mild solubilization, refolding into soluble protein, and final chromatographic purification. The readouts are soluble protein recovery, purity by SDS-PAGE/chromatography, structural recovery by methods such as circular dichroism when used, and biological activity when an assay is available.

The following protocol uses the MTT colorimetric assay as a classic literature-established method for assessing cell viability/metabolic activity in cultured mammalian cells. MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] is reduced by metabolically active cells to a colored formazan product; the amount of formazan is quantified spectrophotometrically and provides an indirect measure of metabolically active viable cells. Importantly, MTT reduction reflects cellular oxidoreductase/metabolic activity rather than an absolute direct count of living cells, so changes in cellular metabolism can alter the signal independently of cell number.