Native electrophoresis studies of different aggregation states of triosephosphate isomerase.

Protein folding is a process mainly due to weak chemical interactions such as repelling of charges, hydrophobic interactions, and hydrogen bonds, which involve reversible disorder-to-order transitions of a polypeptide chain. Although changes between partially folded structures, in order to get a native functional protein, are highly efficient, proteins still may have transiently stable conformations, which yield amorphous oligomers and end in a state of aggregation that may or may not be reversible. Even though the amino acid sequence plays a key role in this process, the microenvironment has an important influence as well, given that chemical modifications by reactive oxygen and nitrogen species produce an inadequate folding.
Triosephosphate isomerase (TIM) is a protein susceptible to nitrotyrosination after which it becomes prone to aggregation; such aggregates have been observed in Alzheimer patients. This suggests that protein folding, oligomer formation and aggregation of this protein plays a key role in the complex biochemical pathway through its structural transitions, as well as in the development of diseases such as Alzheimer. Other research groups and ourselves have been able to provide evidence of protein aggregation in vitro using native electrophoresis and ionic exchange chromatography.
The present work focuses on the characterization of protein aggregates of TIMs from different species. Despite the fact that all TIM proteins described to date have a conserved (α/β) 8 barrel structure, our results show a notable difference in their proclivity to generate one or several aggregation states, when their migration is analyzed using polyacrylamide gradient electrophoresis under native conditions.
Supported by grants 167823 from CONACyT and IN221812 from DGAPA-UNAM