AssayPro—Human Prekallikrein E

Introduction
Prekallikrein (PK), also known as Fletcher factor, is an 88 kDa serine protease that mostly circulates as a complex with high-molecular-weight kininogen (1). Human plasma PK is synthesized as a precursor with a signal peptide of 19 amino acids and the mature circulating protein is a single-chain polypeptide of 619 amino acids. It participates in the surface-dependent activation of blood coagulation, fibrinolysis, kinin generation and inflammation. When cleaved by Factor XIIa, PK is converted into kallikrein with an N-terminal heavy chain (371 amino acids) and a catalytic light chain (248 amino acids) held together by a disulfide bond (2). Plasma kallikrein liberates kinins (bradykinin and kallidin) from the kininogens to regulate vasodilation and inflammation (3). PK deficient patients have prolonged activated partial thromboplastin time without having any bleeding disorder (4).

Principle of the Assay
The AssayMax Human Prekallikrein (PK) ELISA kit is designed for detection of human PK in plasma, serum, saliva, milk, and cell culture samples. This assay employs a quantitative sandwich enzyme immunoassay technique that measures PK in less than 4 hours. A polyclonal antibody specific for PK has been pre-coated onto a 96-well microplate with removable strips. Human PK in standards and samples is sandwiched by the immobilized antibody and the biotinylated polyclonal antibody specific for human PK, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is then washed away and a peroxidase enzyme substrate is added. The color development is stopped and the intensity of the color is measured.