Biotechnology and Bioinformatics (1+1)

Enzyme Linked Immunosorbent Assay (ELISA)

ELISA is an assay for detection or quantitation of an antibody or antigen using a ligand (e.g. an anti- immuunoglobin) conjugate to an enzyme which changes the colour of a substrate . The most common assay involves antibody or antigen coupling to enzymes which gives a colored soluble reaction product. Enzyme such as horse radish peroxidase (HRP) and alkaline phosphatase (AP) which are readily available, stable and have a high turnover number, have been widely employed. One clever play for amplifying the phosphatase reaction is to use NADP as a substrate to generate NAD which now acts as a coenzyme for a second enzyme system. Pyrophosphatase from E. coli provides a good conjugate because the enzyme is not present in tissue, is stable and gives a good reaction color. Chemiluminescent systems based on enzymes such as luciferase can also be applied. A genetically engineered metapyrocatechase-protein A fusion molecule is a recent innovation for detection of Ig G antibodies.