Nanoreporter of an Enzymatic Suicide Inactivation Pathway

Abstract

Enzymatic suicide inactivation, a route of permanent enzyme inhibition, is the mechanism of action for a wide array of pharmaceuticals. Here, we developed the first nanosensor that selectively reports the suicide inactivation pathway of an enzyme. The sensor is based on modulation of the near-infrared fluorescence of an enzyme-bound carbon nanotube. The nanosensor responded selectively to substrate-mediated suicide inactivation of the tyrosinase enzyme via bathochromic shifting of the nanotube emission wavelength. Mechanistic investigations revealed that singlet oxygen generated by the suicide inactivation pathway induced the response. We used the nanosensor to quantify the degree of enzymatic inactivation by measuring response rates to known small molecule tyrosinase modulators. This work resulted in a new capability of interrogating a specific route of enzymatic death. Potential applications include drug screening and hit-validation for compounds that elicit or inhibit enzymatic inactivation, and single-molecule measurements to assess population heterogeneity in enzyme activity.

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“…Yaari et al demonstrated the first SWCNT-based sensor that reports the degree of enzymatic suicide inactivation. [201] The approach was based on enzyme-bound SWCNTs,w hich report fluorescence modulations by quenching and redshifting selectively in response to substrate-mediated suicide inactivation of tyrosinase.M echanistic insights revealed that the red-shifted response is most likely ar esult of the generation of singlet oxygen during the enzymatic reaction, which leads to the binding of ssDNAo nt he SWCNT surface. [132]…”

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