Signosis NAD⁺ Enzyme Combo Assay Kit is designed to measure NAD⁺ levels as well as the activity of two key NAD⁺-dependent enzymes, SIRT and NAMPT, in one platform. SIRT is measured using a specially designed FRET-based peptide substrate and NAMPT is detected using a series of enzyme reactions ending with NADH. NAD⁺ levels are measured using Signosis' popular NAD⁺/NADH Assay Kit.