"Double gating"--a concept for enzyme-responsive imaging probes aiming at high tissue specificity

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Biology

Background:

• Enzyme-activated probes offer enhanced specificity in biological imaging.
• Pre-existing probes often lack the ability to provide multi-enzyme-dependent activation.
• Nature utilizes pre-pro-protein strategies for biological regulation.

Purpose of the Study:

• To develop a novel activatable imaging probe with a unique "off-on" fluorescence response.
• To demonstrate the probe's ability to discriminate cells based on the presence of two specific enzymes.
• To introduce the concept of "pre-pro-fluorescent" molecular probes.

Main Methods:

• Design and synthesis of a novel activatable fluorescent probe.
• Sequential enzymatic cleavage by two distinct enzymes (β-d-galactosidase and leucine amino-peptidase).
• Fluorescence microscopy and imaging to detect probe activation and cellular discrimination.

Main Results:

• The developed probe exhibits an "off-on" fluorescence response exclusively after sequential enzymatic conversion.
• The probe successfully differentiates cells expressing both target enzymes from those lacking one or both.
• A precipitating fluorescent tag is released upon successful dual enzymatic activation.

Conclusions:

• The novel "pre-pro-fluorescent" probe represents a new archetype in activatable molecular imaging.
• This technology offers enhanced specificity and provides additional information compared to conventional probes.
• The probe's ability to discriminate cells based on dual enzyme activity opens new avenues for biological research and diagnostics.