Practice question

Fluorescent reporters differ markedly in substrate requirement and handling. Enzymes like horseradish peroxidase and alkaline phosphatase need exogenous chromogenic or chemiluminescent substrates TMB, pNPP, BCIP to produce detectable color or light signal. Luciferase requires luciferin and ATP to emit bioluminescence. Green Fluorescent Protein from jellyfish Aequorea victoria forms its internal chromophore autocatalytically through cyclization, requiring only excitation light near 488 nanometers to emit bright green light without added chemicals, fixation or permeabilization. This self contained fluorescence makes GFP ideal for live cell tracking.