What is "prekallikrein"

n. A serine protease that complexes with high-molecular-weight kininogen; the precursor of plasma kallikrein.

Prekallikrein (PK), also known as Fletcher factor, is an 85,000 Mr serine protease that complexes with high-molecular-weight kininogen. PK is the precursor of plasma kallikrein, which is a serine protease that activates kinins. PK is cleaved to produce kallikrein by activated Factor XII (Hageman factor).