Plant protein interactions studied using AFM force spectroscopy: nanomechanical and adhesion properties

The present work was focused on the nanomechanical and adhesion properties of the napin (2S albumin) and cruciferin (12S globulin) rapeseed (Brassica napus L.) proteins, respectively, a low and high molecular weight seed protein. Using chemically modified AFM tips, force spectroscopy experiments demonstrated notable differences in the tip-protein interaction strength with regard to the nature of the protein and pH of the aqueous environment. The results clearly underline the role of residence time and electrostatic interactions in the protein-protein adhesion force. Although the nanomechanical experiments concerned more than a single molecule, unfolding length and force characteristics of the rapeseed proteins have been statistically found to be sensitive to the structural properties of the protein. This study provides insight into the characterization of rapeseed proteins and then a better knowledge of their interaction and assembling at the nanoscale range.