Lactate dehydrogenase (LDH) is an oxidoreductase (EC 1.1.1.27) present in a wide variety of organisms. LDH catalyzes the interchange of lactate to pyruvate, with the concomitant interconversion of NAD+ to NADH. LDH is present in many organs and tissues including liver, heart, pancreas, kidneys, skeletal muscles, brain, and blood cells. When illness or injury damages cells, LDH may be released into the bloodstream, causing a rise of LDH level in blood. Elevated LDH in serum can indicate a number of unfavorable medical conditions like cerebral attack, heart attack, hepatitis, muscular dystrophy, hemolytic anemia and even certain cancers. Therefore, quantitation of LDH activity has significant clinical importance. Assay Genie's Lactate Dehydrogenase Colorimetric Assay kit, offers a simple and sensitive assay that can detect and quantify the enzymatic activity of LDH. In this assay, LDH oxidizes a substrate utilizing NAD as cofactor. The reduced cofactor (NADH) reacts with a chromophore producing a stable color (OD: 500 nm) that is directly proportional to LDH activity. The assay is suitable to detect the enzymatic activity as low as 0.08 mU in various biological samples

Figure: (a) NADH Standard Curve; (b) Kinetic profiles of LDH activity for LDH Positive Control (1:40 dilution, 1 µl) and 2 µl human serum, loaded to well directly without any prior treatment. For background control, Assay Buffer (Buffer) without the Substrate Mix Solution was run in parallel.