Biochemical characterization of human kallikrein 8 and its possible involvement in the degradation of extracellular matrix proteins.
Human kallikrein 8 (KLK8) is a member of the human kallikrein gene family of serine proteases, and its protein, hK8, has recently been suggested to serve as a new ovarian cancer marker. To gain insights into the physiological role of hK8, the active recombinant enzyme was obtained in a pure state for biochemical and enzymatic characterizations. hK8 had trypsin-like activity with a strong preference for Arg over Lys in the P1 position, and its activity was inhibited by typical serine protease inhibitors. The protease degraded casein, fibronectin, gelatin, collagen type IV, fibrinogen, and high-molecular-weight kininogen. hK8 also converted human single-chain tissue-type plasminogen activator (65 kDa) to its two-chain form (32 and 33 kDa) by specifically cleaving the peptide bond Arg275-Ile276. This conversion resulted in a drastic increase in the activity of the activator toward the fluorogenic substrate Pyr-Gly-Arg-MCA and plasminogen in the absence of fibrin. Our findings suggest that hK8 may be implicated in ECM protein degradation in the area surrounding hK8-producing cells.
Rajapakse
Sanath
S
Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
Ogiwara
Katsueki
K
Takano
Naoharu
N
Moriyama
Akihiko
A
Takahashi
Takayuki
T
D001120:Arginine / Q000737:chemistry; D002364:Caseins / Q000737:chemistry; D024141:Collagen Type IV / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005260:Female; D005340:Fibrinogen / Q000737:chemistry; D005353:Fibronectins / Q000737:chemistry; D005780:Gelatin / Q000737:chemistry; D006801:Humans; D007610:Kallikreins / Q000032:analysis / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity; D010959:Tissue Plasminogen Activator / Q000737:chemistry / Q000378:metabolism
D002364:Caseins; D024141:Collagen Type IV; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D011993:Recombinant Fusion Proteins; D015842:Serine Proteinase Inhibitors; D005780:Gelatin; D005340:Fibrinogen; D001120:Arginine; C094799:KLK8 protein, human; D007610:Kallikreins; D010959:Tissue Plasminogen Activator