Human PDE5A (GenBank Accession No. NM_001083), full length with N-terminal GST tag, expressed in a Baculovirus infected Sf9 cell expression system. Specific Activity: ~3000 pmol/min/ug Activity: Quantified by 5-nucleotidase cleaving the 5GMP product and releasing the phosphate group which was detected by Malachite Green Reagent. Unit Definition: One unit is defined as the amount of P4072-05A that will convert 1pmole of 3,5-cGMP to 5-GMP per min at 37C under Assay conditions. Assay Conditions: 10mM Tris-HCl, pH 7.4, 10mM MgCl2, 200uM cGMP, 0.1mg/ml BSA, 0.05% Tween-20, 200uM cGMP and serial dilutions of PDE5A at 37C for 20 minutes. Applications: Useful for the study of enzyme kinetics, screening inhibitors, and selectivity profiling. Recommended Dilutions: Optimal dilutions to be determined by the researcher. Storage and Stability: Aliquot to avoid repeated freezing and thawing and store at -70C. Aliquots are stable for 6 months after receipt. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.