Factors influencing the hemolysis of human erythrocytes by cardiotoxins from Naja naja kaouthia and Naja naja atra venoms and a phospholipase A2 with cardiotoxin-like activities from Bungarus fasciatus venom

Toxicon ◽  
1989 ◽  
Vol 27 (2) ◽  
pp. 247-257 ◽  
Author(s):  
Ming-shi Jiang ◽  
Jeffrey E. Fletcher ◽  
Leonard A. Smith
Keyword(s):  
Phospholipase A2 ◽  
Human Erythrocytes ◽  
Naja Naja ◽  
Factors Influencing ◽  
Naja Kaouthia ◽  
Naja Atra

Immunochemical properties of Naja naja atra (Taiwan cobra) phospholipase A2 using polyclonal and monoclonal antibodies

Toxicon ◽  
1992 ◽  
Vol 30 (2) ◽  
pp. 151-159 ◽  
Author(s):  
C.C. Yang ◽  
L.S. Chang ◽  
P.L. Ong ◽  
T.H. Tung
Keyword(s):  
Monoclonal Antibodies ◽  
Phospholipase A2 ◽  
Naja Naja ◽  
Naja Atra

scholarly journals Zinc and barium inhibit the phospholipase A2 from Naja naja atra by different mechanisms

1994 ◽  
Vol 301 (2) ◽  
pp. 503-508 ◽  
Author(s):  
M Mezna ◽  
T Ahmad ◽  
S Chettibi ◽  
D Drainas ◽  
A J Lawrence
Keyword(s):  
Phospholipase A2 ◽  
Binding Sites ◽  
Alternative Model ◽  
Competitive Inhibitor ◽  
Enzymic Activity ◽  
Crystallographic Analysis ◽  
Kinetic Characteristics ◽  
Naja Naja ◽  
Pla2 Enzyme ◽  
Naja Atra

The mode of inhibition of the phospholipase A2 (PLA2) enzyme from the Chinese cobra (Naja naja atra) by Zn2+ is qualitatively different from inhibition by Ba2+. Inhibition by Ba2+ shows the kinetic characteristics of a conventional competitive inhibitor acting to displace Ca2+ from a single essential site, but Zn2+ has the paradoxical property of being more inhibitory at high than at low Ca2+ concentration. Kinetic analysis of the Ca(2+)-dependence of enzymic activity shows a bimodal response, indicating the presence of two Ca(2+)-binding sites with affinities of 2.7 microM and 125 microM respectively, and we propose that these can be identified with the two Ca(2+)-binding sites revealed by crystallographic analysis [White, Scott, Otwinowski, Gleb and Sigler (1990) Science 250, 1560-1563]. The results are consistent with the model that the enzyme is activated by two Ca2+ ions, one that is essential and can be displaced by Ba2+, and one that modulates the activity by a further 5-10-fold and which can be displaced by Zn2+. An alternative model is also presented in which the modulating Zn(2+)-binding site is a phenomenon of the lipid/water interface.

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