Using fluorescence correlation spectroscopy, we show that the diffusive movement of single enzyme molecules of urease and catalase increases in the presence of their respective substrates, in a concentration-dependent manner. A similar enhancement in diffusion was observed for T4 DNA polymerase-DNA template complex in the presence of a nucleoside triphosphate substrate. Employing a microfluidic device to generate substrate concentration gradient, we show that urease, catalase, and T4 DNA polymerase molecules spread towards areas of higher substrate concentration, a form of chemotaxis at the single molecule scale. Using glucose oxidase and glucose to generate a hydrogen peroxide gradient, we induce the migration of catalase towards glucose oxidase. Further, we show that T4 DNA polymerase molecules migrate towards regions of higher magnesium concentration, a cofactor for the polymerase.

Single enzyme propulsion

244th National Meeting (2012)

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