Question

What is the enzyme HRP?

and What product indicates that there has been an antigen-antibody reaction.

Answer 1

Horse Radish Peroxidase -HRP- is an enzyme isolated from the root of the plant-horseradish.

It is a metalloenzyme- has one iron heme group and two calcium atoms.

Peroxidase are enzymes those use H2O2 as electron acceptor. HRP oxidises both organic and inorganic compound by using hydrogen peroxide.

The property of HRP to show fluorescence or dark coloured complex when conjugated with a substrate makes it a option for using in applications such as western blot, ELISA. It helps in detecting the protein even in smaller concentration.

Antigen antibody reaction can be identified by different reactions according to the test done.

Agglutination, precipitation, fluorescence,neutralisation are some of the reactions through which we can find antigen antibody reaction.

In case of ELISA where we use HRP, immuno fluorescence indicates Ag-Ab reaction. The colour formation indicates the reaction.

For ex- in indirect ELISA

The antigen is coated in the well and primary antibody ia added first. It is incubated and washed and then we will add secondary antibody coated with HRP. This secondary antibody binds specifically to the primary antibody. When substrate such as TMB is added to the well, HRP oxidises the substrate producing a detectable colour. So the colour indicates the antigen antibody reaction.