Enzymatic reactions dictated by the 2D membrane environment

Abstract

The cell membrane is a fundamental component of cellular architecture. Beyond serving as a physical barrier that encloses the cytosol, it also provides a crucial platform for numerous biochemical reactions. Due to the unique two-dimensional and fluidic environment of the membrane, reactions that occur on its surface are subject to specific physical constraints. However, the advantages and disadvantages of membrane-mediated reactions have yet to be thoroughly explored. In this study, we reconstitute a classic proteolytic cleavage reaction at the membrane interface, designed for the real-time, single-molecule kinetic analysis. The interactions between the enzyme and substrate near the membrane are examined under different classic scenarios. Our findings reveal that while the membrane environment significantly enhances enzymatic activity, it also imposes diffusion limitations that reduce this activity over time. By adjusting the enzymes membrane affinity to an intermediate level, we enable the enzyme to "hop" on the membrane surface, overcoming these diffusion constraints and sustaining high enzymatic activity with faster kinetics. These results provide critical insights into the role of the cell membrane in regulating biochemical reactions and can be broadly applied to other membrane-associated interactions.