Evidence for New Enantiospecific Interaction Force in Chiral Biomolecules

  Yael Kapon  ,  Abhijit Saha  ,  Tal Duanias-Assaf  ,  Thijs Stuyver  ,  Amir Ziv  ,  Tzuriel Metzger  ,  Shira Yochelis  ,  Sason Shaik  ,  Ron Naaman  ,  Meital Reches  ,  Yossi Paltiel  
Bar Ilan University

Enantiospecific biorecognition interactions are key to many biological events. Commonly, bio-affinity values, measured in these processes, are higher than those calculated by available methods. We report here the first direct measurement of the interaction force between right and left handed helical polyalanine peptides using atomic force microscope (AFM) and calculations based on a simple theoretical model. A force difference of 60pN between same and opposite enantiomer interactions is measured.  Additional measurements show spin dependency and fast decay of the interaction term, consistent with spin exchange interactions. This short range enantiospecific interaction term is especially relevant in crowded biological systems. The results shed light on the importance of spin and exchange interactions in biological processes, providing explanation to the discrepancies between past calculations and experiments.