Biochemical Properties of a Bushmaster Snake Venom Serine Proteinase (LV-Ka), and Its Kinin Releasing Activity Evaluated in Rat Mesenteric Arterial Rings

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概要

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• A serine proteinase with kallikrein-like activity (LV-Ka) has been purified to homogeneity from bushmaster snake (Lachesis muta muta) venom. Physicochemical studies indicated that LV-Ka is a single chain glycoprotein with a molecular mass (Mr) of 33 kDa under reducing conditions which was reduced to 28 kDa after treatment with N-Glycosidase F (PNGase F). LV-Ka can be bounded and neutralized by serum α2-macroglobulin (α2-M), a prevalent mammalian protease inhibitor that is capable of forming a macromolecular complex with LV-Ka (Mr >180 kDa). Cleavage of α2-M by the enzyme resulted in the formation of 90-kDa fragments. The proteolytic activity of LV-Ka against dimethylcasein could be inhibited by α2-M, and the binding ratio of the inhibitor:enzyme complex was found to be 1:1. The Michaelis constant, Km, and catalytic rate constant, kcat, of LV-Ka on four selective chromogenic substrates were obtained from Lineweaver-Burk plots. LV-Ka exhibits substrate specificities not only for the glandular kallikrein H-D-Val-Leu-Arg-pNA (S-2266) but also for the plasmin substrates S-2251 and Tos-Gly-Pro-Lys-pNA. Bovine kininogen incubated with LV-Ka generated a polypeptide that dose dependently contracted mesenteric arterial rings from spontaneously hypertensive rats (SHR) in a similar way as bradykinin (BK) does. As it happens with BK, LV-Ka generated polypeptide was inhibited by HOE-140, a bradykinin B2-receptor antagonist and by indomethacin, a cyclo-oxygenase inhibitor. These results strongly suggest that the polypeptide generated by LV-Ka by cleavage of bovine kininogen is bradykinin. In addition, our studies may help to understand the mechanism of action involved in hypotension produced by envenomation of bushmaster snake.

著者

• SANCHEZ Eladio

  Research and Development Center, Ezequiel Dias Foundation

• Felicori Liza

  Research And Development Center Ezequiel Dias Foundation

• Bello Cynthia

  Research And Development Center Ezequiel Dias Foundation

• Almeida Alvair

  Vascular Smooth Muscle Laboratory Department Of Physiology And Biophysics Icb Federal University Of

• Sanchez Eladio

  Research And Development Center Ezequiel Dias Foundation

• Magalhaes Arinos

  Research And Development Center Ezequiel Dias Foundation

• Magalhaes Henrique

  Faculty Of Pharmacy Federal University Of Minas Gerais

• Weinberg Maria

  Vascular Smooth Muscle Laboratory Department Of Physiology And Biophysics Icb Federal University Of

• ALMEIDA Alvair

  Vascular Smooth Muscle Laboratory, Department of Physiology and Biophysics, ICB, Federal University of Minas Gerais

• Weinberg Maria

  Vascular Smooth Muscle Laboratory, Department of Physiology and Biophysics, ICB, Federal University of Minas Gerais

関連論文

• Endothelium-Dependent Relaxation of Rat Mesenteric Arterial Rings by a Phoneutria nigriventer Venom Fraction
• Biochemical Properties of a Bushmaster Snake Venom Serine Proteinase (LV-Ka), and Its Kinin Releasing Activity Evaluated in Rat Mesenteric Arterial Rings
• Biochemical Properties of a Bushmaster Snake Venom Serine Proteinase (LV-Ka), and Its Kinin Releasing Activity Evaluated in Rat Mesenteric Arterial Rings

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