Amyloid aggregation and secondary structure changes of liver cystatin: Acidic denaturation and TFE induced studies

Abstract

A cysteine proteinase inhibitor has been purified by affinity chromatography from the liver of buffalo. Liver cystatin is subjected to incubation at low pH with co-solvent TFE, where we have studied the effect on the conformation, activity and tendency to form aggregates or fibrils. ANS fluorescence was used to study conformational changes. The fibril formation and aggregation was studied using ThT assay, CD, FTIR and fluorescence spectroscopy. At pH 3.0 there was no fibril formation though aggregates were formed but in presence of TFE fibrils appeared. At pH 2.0 and 1.0, TFE induced rapid fibril formation compared to only acid induced state as assessed by Thioflavin T (ThT) fluorescence.TFE stabilized each of the three acid induced intermediates at predenaturational concentrations (20%) and accelerated fibril formation. Solvent conditions had a profound effect on the tendency of liver cystatin to produce fibrils and aggregation.

Communicated by Ramaswamy H. Sarma

Keywords:

• CD spectroscopy
• FTIR
• Cystatin
• amyloid
• aggregation

Acknowledgements

The author is highly thankful to the Department of biochemistry, A.M.U for all the facilities provided. The author is highly thankful to UGC and DST for grants. The department of applied physics, A.M.U needs a special mention for all the facilities provided by them.

Disclosure statement

The authors declare that they have no conflict of interest.