Purification and characterisation of blarinasin, a new tissue kallikrein-like protease from the short-tailed shrew Blarina brevicauda: comparative studies with blarina toxin

Authors:
  • YOYuushi Okumura
    Yuushi Okumura
  • SOSatoshi D. Ohdachi
    Satoshi D. Ohdachi
  • YOYuichi Oba
    Yuichi Oba
  • MYMichiyasu Yoshikuni
    Michiyasu Yoshikuni
  • YNYasuo Nakamura
    Yasuo Nakamura
  • HKHiroshi Kido
    Hiroshi Kido
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Abstract
A new tissue kallikrein-like protease, blarinasin, has been purified from the salivary glands of the short-tailed shrew Blarina brevicauda. Blarinasin is a 32-kDa N-glycosylated protease with isoelectric values ranging between 5.3 and 5.7, and an optimum pH of 8.5 for enzyme activity. The cloned blarinasin cDNA coded for a pre-pro-sequence and a mature peptide of 252 amino acids with a catalytic triad typical for serine proteases and 43.7-54.0% identity to other mammalian tissue kallikreins. Blarinasin preferentially hydrolysed Pro-Phe-Arg-4-methylcoumaryl-7-amide (MCA) and N-tert-butyloxycarbonyl-Val-Leu-Lys-MCA, and preferentially converted human high-molecular-weight kininogen (HK) to bradykinin. The activity of blarinasin was prominently inhibited by aprotinin (K(i) =3.4 nM). A similar kallikrein-like protease, the lethal venom blarina toxin, has previously been purified from the salivary glands of the shrew Blarina and shows 67.9% identity to blarinasin. However, blarinasin was not toxic in mice. Blarinasin is a very abundant kallikrein-like protease and represents 70-75% of kallikrein-like enzymes in the salivary gland of B. brevicauda.

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