AffinityImmuno Products

Introduction

Fetuin-A, encoded by the AHSG gene, is an abundant liver-derived plasma glycoprotein that circulates at high concentration and was originally characterized for its affinity for calcium and phosphate ions. By binding these minerals and forming soluble complexes, together with matrix Gla protein, fetuin-A keeps calcium phosphate from precipitating in blood and soft tissue, making it one of the body’s principal circulating inhibitors of unwanted, ectopic vascular and tissue calcification. Beyond mineral handling, it supports endocytosis and opsonization of particles for immune clearance, contributes to normal bone and brain development, and has been implicated in insulin receptor signaling, with population studies linking AHSG variation to differences in body composition and leanness. Because of its dual roles in mineral metabolism and metabolic regulation, fetuin-A is studied both as a marker of vascular calcification risk and as a factor in insulin resistance and related cardiometabolic disease.

Because fetuin-A is one of the body’s principal circulating inhibitors of ectopic vascular calcification, it’s studied both as a marker of cardiovascular calcification risk and, separately, as a factor in insulin resistance — making this assay relevant to cardiometabolic and renal (CKD-associated calcification) research alike.

Principle of the Assay

This kit uses a sandwich enzyme immunoassay format in which the microtiter plate wells are pre-coated with a capture antibody specific to human AHSG/fetuin-A. Standards or samples are pipetted into the appropriate wells together with a biotin-conjugated detection antibody that also recognizes human AHSG/fetuin-A. Avidin conjugated to horseradish peroxidase (HRP) is then added to each well and allowed to incubate, linking enzymatic activity to any captured analyte complex. Upon addition of TMB substrate solution, a colorimetric signal develops exclusively in wells containing human AHSG/fetuin-A, the biotin-conjugated detection antibody, and avidin-HRP. The enzymatic reaction is stopped by the addition of a sulphuric acid stop solution, and absorbance is measured spectrophotometrically at 450 nm (± 10 nm). Sample concentrations are calculated by comparing the optical density of each sample against a standard curve.