Selective labeling of histidine by a designed fluorescein-based probe

Area of Science:

• Analytical Chemistry
• Biochemistry
• Organic Chemistry

Background:

• Histidine is a crucial amino acid with diverse biological roles.
• Selective and sensitive detection methods for histidine are essential in biological and clinical research.
• Existing methods for histidine detection may lack specificity or sensitivity.

Purpose of the Study:

• To synthesize and characterize a novel fluorescent probe, 3-epoxypropoxy fluorescein (EPF).
• To evaluate the probe's selectivity and sensitivity for labeling histidine.
• To demonstrate the application of EPF for histidine detection in biological samples.

Main Methods:

• Synthesis of 3-epoxypropoxy fluorescein (EPF) with a fluorescein fluorophore and an epoxy labeling group.
• Selective reaction of EPF with histidine in alkaline media.
• Fluorescence intensity measurements for histidine detection.
• Application of EPF for labeling histidine in human serum.
• Comparison with histidine-nickel complex adsorptive voltammetry.

Main Results:

• EPF selectively reacts with histidine in alkaline media, causing a significant increase in fluorescence.
• The fluorescence enhancement is attributed to the basic molecular environment created by histidine addition.
• Successful fluorescent labeling of histidine in human serum was achieved.
• The method demonstrated high precision (relative S.D. of 1.8%) and a wide linear range (0.007-10 muM).
• A low detection limit of 0.001 muM (S/N=3) was achieved.

Conclusions:

• EPF is a novel and effective fluorescent probe for the selective detection of histidine.
• The probe offers high sensitivity, precision, and a broad linear range for histidine quantification.
• EPF shows promise for histidine analysis in biological and clinical applications.