Plasma kallikrein, also known as Fletcher factor or kallikrein B1 (KLKB1), is a serine endopeptidase, like its homologs tissue kallikrein and kallikrein-related peptidases (KLKs). Its physiological role is to catalyze the release of kinins and other vasoactive peptides. KLKB1 Protein, Mouse, Recombinant (His) is expressed in HEK293 mammalian cells with C-His tag. The predicted molecular weight is 70.3 kDa and the accession number is P26262.