Protective effect of 3,5,3'-triiodothyroacetic and 3,5,3',5'-tetraiodothyroacetic acids on serum albumin fibrillation.

Inhibition or reversion of protein self-aggregation has been suggested as a possible preventive mechanism against amyloid diseases, and many efforts are underway to found out molecules capable to restrain the protein aggregation process. In this paper, the inhibitory effects of thyroid hormone analogues on heat-induced fibrillation process of serum albumin are reported. Among the analogues tested, 3,5,3',5'-tetraiodothyroacetic and 3,5,3'-triiodothyroacetic acid showed the most important inhibitory effects on amyloid formation. Thyroxine exhibits a lesser protective effect, while 3,5,3'-triiodothyronine showed no significant inhibition. The gaining of a negative charge together with a size reduction of the hormone molecule could play an essential role in the inhibition of fibrils formation. According to infrared spectroscopy results, the thyroid hormones analogues protective effects proceed via the stabilization of the protein native structure. The current work demonstrates the effectiveness of naturally occurring molecules in the inhibition of albumin fibril formation.