Exploring the potency of the naturally occurring polyphenol curcumin as a probe for protein aggregation in crowded...

Conventional dyes such as thioflavin T, ANS, and Congo Red etc. have mostly been used to monitor protein aggregation. In this work, we have tried the naturally occurring polyphenol, curcumin, for probing the aggregation of the serum protein bovine serum albumin (BSA) in crowded environments. The distinctive spectral profile of this polyphenol in response to varying aggregating scenario is indicative of its high sensitivity towards detection of aggregates. We have also gained possible insights into the heterogeneity of the aggregation mixture, that is, the different species that are present simultaneously at any instant of time by fitting curcumin's emission spectra to a sum of Gaussians in diverse aggregating conditions. SEM study reveals that the morphology of aggregates formed in presence of different crowding agents became independent of the nature of the crowder on prolonged incubation. To overcome the aqueous insolubility barrier of the molecular probe (curcumin), β-cyclodextrin, which is known to complex with curcumin, was also added to the reaction mixture.