Mechanical Unfolding and Amorphous Aggregation of Protein in a Very Low DC Field

A common theme for the effect of electric field on the structure and conformation of proteins is lacking due to a myriad of conflicting reports emerging from different protein systems subjected to different frequencies and strengths of the field (0.8 -10⁸ V cm^-1), which may be pulsed for a few nano- to microseconds or applied continuously up to several hours. It is however necessary to find a common theme because of the increasing use of electric field not only to understand Stark-like electro-optic effects in large molecules but also in food processing technology, and perhaps in the disruption of amyloid bodies in Alzheimer's condition. This study finds an optimized condition of 1.3 V cm^-1 DC field, in which the electrophoretic mobility is ∼1.2 mm h^-1, and systematically shows electrophoretic, electrochemical, and unfolding effects at different levels of cytochrome c structure within ∼90 min of turning the field on. Interestingly, the protein undergoes amorphous aggregation concomitant with a high degree of denaturation. In support of this suggestion, data for myoglobin and trypsin are also presented. Effort has been made to separate out the chemical and physical effects of the electric field.