The Study Of The Relationship Of Metal Ions With The Activity And Structure Of The Metalloproteinase AHPM From The Agkistrodon Halys Pallas

Snake venom is a class of complex mixture composed of proteins, peptides, inorganic compounds and metal ions. Snake venom metalloproteinase is one of the main components of snake venom. Its catalytic activity is regulated by metal ions (zinc and calcium ions). AHPM is a kind of metalloproteinase from venom of Agkistrodon Halys Pallas with fibrinogenolytic activity and contains zinc and calcium ions. In this article, we have investigated the effects of zinc and calcium ions on the fibrinogenolytic, fluorescence activity and the structural stability of apo-AHPM.In the first chapter, we briefly review the research history of metalloproteinases, including classification, function, X-ray structure, and the relationship with the structure of the integrin. At the end of this chapter, we also introduce the application prospect of snake venom metalloproteinases. Some of the snake venom metalloproteinases even have been developed to the third phase of clinical trias for treating nerve peripheral arterial occlusive disease and stroke.In the second chapter, we have reviewed snake venom antihypertensive protein and small peptides in the past decade. With the increasement of hypertension incidence worldwide, it is urgent to seek for all kinds of new type of antihypertensive drugs to solve the important global health problem. Snake venom of antihypertensive peptides can provide us with novel lead compounds to design the antihypertensive drugs.So far, there have made great progress in the structure, function and mechanism research of antihypertensive peptide. In recent ten years, some new types of antihypertensive peptides have been identified from snake venom, the venom antihypertensive peptides are divided into five classes:bradykinin potentiating peptides, natriuretic peptides, sarafotoxins, Phospholipases A2 and L-type Ca2+ channel blockers. Some of them have been used as convenient tools to explore the complicated mechanism of cardiovascular disease, other antihypertensive peptides have been used as clinical diagnostic biomarkers or drugs to treat high blood pressure and cardiovascular disease.This review provide an overview of the structure, function and mechanism of snake venom antihypertensive peptide of current understanding.In the third chapter, we have studied the effects of zinc and calcium ions on fluorescence, fibrinogenolytic activity, and structural stability of apo-AHPM by CD spectrum, fluorescence titration and ITC measurement. The results show that only zinc ions activate apo-AHPM, the activation of calcium ions is little and almost negligible. Also only zinc ions have a more important role in maintaining AHPM structural stability, the role of calcium ion is small. In combination with the apo-AHPM, Zinc ions have two classes of binding sites, while calcium ions may have only one kind of binding site. It is worth noting that the common point of the two kinds of ions is that both of them make the trouth of CD spectra of apo-AHPM cause a blue shift, this indicates that they have led to some change on the conformation of apo-AHPM. Zinc and calcium ions can promote the combination with apo-AHPM each other, but the combination of zinc ions with apo-AHPM is more stable. However, in the aspect of combining heat with apo-AHPM, that of calcium ions is more than that of zinc ions.