Effect of calcium on proteolytic activity and conformation of hemorrhagic toxin I from five pace snake (Agkistrodon acutus) venom.
AaHI, a proteolytic hemorrhagic toxin from A. acutus venom, contains one g-atom Zn per mole protein and 2 g-atoms Ca per mole protein. AaHI is activated by calcium and slightly inhibited by zinc. When treated with EDTA, AaHI is completely inactivated. When dialyzed against 1,10-O-phenanthroline, 50-80% of the metal content and activities are lost, while 90% of the hemorrhagic and proteolytic activities are retained when dialyzed against 1,10-O-phenanthroline containing 5mM Ca2+. The results suggest that calcium is essential for the hemorrhagic and proteolytic activities. The circular dichroism spectra show that calcium may play an important role in maintaining a proper structure for AaHI. The function of zinc is not clear.
D000818:Animals; D002118:Calcium / Q000032:analysis / Q000502:physiology*; D002364:Caseins / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D055598:Chemical Phenomena; D002621:Chemistry; D002942:Circular Dichroism; D003435:Crotalid Venoms / Q000378:metabolism* / Q000494:pharmacology; D006470:Hemorrhage / Q000139:chemically induced; D008670:Metals / Q000032:analysis / Q000502:physiology; D010447:Peptide Hydrolases / Q000378:metabolism*; D011487:Protein Conformation
C031442:Agkistrodon venoms; D002364:Caseins; D002614:Chelating Agents; D003435:Crotalid Venoms; D008670:Metals; C032814:hemorrhagin components (Crotalid); D010447:Peptide Hydrolases; D002118:Calcium