GMP-Fluorescein conjugate calibrator is desigend to use with our green fluorescent FAM-cGMP PDE V substrate, a cGMP derivative that is a specific substrate for phosphodiesterase (PDE) V (#Cat: 13604). This GMP-Fluorescein conjugate calibrator is the hydrolyzed product of FAM-cGMP PDE V substrate (#Cat: 13604) by PDE V. It is used to calibrate the hydrolysis rate of FAM-cGMP PDE V substrate (#Cat: 13604) by PDE V.