Impulsive Enzymes: A New Force in Mechanobiology

Conversion of substrate to products by enzymatic catalysis is a fundamental process in nature. Enzyme-based biological motors perform specific cellular functions, such as DNA synthesis and vesicular transport with great precision and efficiency. ATP fueled biological motors also facilitate directed movement of cells toward chemicals or light. A key question is whether a single enzyme molecule can generate sufficient mechanical force during catalysis to perform as nanomotor, in addition to its primary function as catalyst for reactions. Herein with a series of experiments, we demonstrate that active enzymes at the single molecule level can transduce enough mechanical force to propel themselves or other larger structures autonomously in solutions. More significantly, enzymes and larger hybrid structures display collective chemotactic migration towards specific targets in the presence of substrate concentration gradients- a situation that parallels the chemotaxis of whole cells.Controlled energy transduction at the single molecule level can result in a variety of novel phenomena that are significant both from the scientific and technological standpoints. For example, enzyme chemotaxis should find wide applicability in targeted molecular transport and delivery. Chemotactic separation of biomolecules from a mixture has been demonstrated to be sensitive enough to sort out molecules possessing identical physical properties, which cannot otherwise be accomplished using currently known separation techniques. Enzymes immobilized over a surface can perform directional fluid pumping within microfluidic chambers that can be harnessed to substantially enhance the sensitivity of biomolecular detection. Finally, enhanced diffusion of particles dispersed in active enzyme solutions suggests that non-traditional enzymatic impulses could be an important source of force in the cytosolic environments, driving processes related to stochastic pulsing and convection of cytoplasmic fluid.