The Human HtrA Serine Peptidase (HTRA1) ELISA Kit is a sandwich enzyme immunoassay for the in vitro quantitative measurement of HTRA1 in human serum, plasma and other biological fluids.The microtiter plate provided in this kit has been pre-coated with an antibody specific to HTRA1. Standards or samples are then added to the appropriate microtiter plate wells with a biotin-conjugated antibody specific to HTRA1. Next, Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. After TMB substrate solution is added, only those wells that contain HTRA1, biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of sulfuric acid solution and the color change is measured spectrophotometrically at a wavelength of 450nm ± 10nm. The concentration of HTRA1 in the sample is then determined by comparing the O.D. of the sample to the standard curve.