Separation of proteins by square-wave pulsed field and inversion field capillary electrophoresis

Background Capillary electrophoresis (CE) is an effective method for protein analysis. Although previous researchers have proved that the separation performance of large DNA molecules was improved by pulsed field capillary electrophoresis (PFCE), there is lack of research about proteins separation by PFCE. Methods Herein, we systematically investigated the separation performance of proteins sized from 44 kDa to 200 kDa under square wave and inversion electric field, respectively. Findings Results showed that for pulsed electric field with same forward and backward time duration, there was a resonance frequency for protein molecule re-orientation and applied frequency, and the apparent mobility ( μ ) was the lowest at the resonance frequency. μ was positively correlated to modulation depth ( M ) if M was below 200%, while μ was negatively correlated to M if M was higher than 200%. For CE with same forward and backward voltage, it demonstrated that μ dropped as M went up, but the separation performance for proteins with high molecular mass improved. Through PFCE, albumin and α- globulins in human serum were also resolved within 7 min. Such a work may shed new light on the analysis of proteins by PFCE.