Batroxase, a new metalloproteinase from B. atrox snake venom with strong fibrinolytic activity

The structures and functional activities of metalloproteinases from snake venoms have been widely studied because of the importance of these molecules in envenomation. Batroxase, which is a metalloproteinase isolated from Bothrops atrox (Para) snake venom, was obtained by gel filtration and anion exchange chromatography. The enzyme is a single protein chain composed of 202 amino acid residues with a molecular mass of 22.9 kDa, as determined by mass spectrometry analysis, showing an isoelectric point of 7.5. The primary sequence analysis indicates that the proteinase contains a zinc ligand motif (HELGHNLGISH) and a sequence C164I165M166 motif that is associated with a "Met-turn" structure. The protein lacks N-glycosylation sites and contains seven half cystine residues, six of which are conserved as pairs to form disulfide bridges. The three-dimensional structure of Batroxase was modeled based on the crystal structure of BmooMP alpha-I from Bothrops moojeni. The model revealed that the zinc binding site has a high structural similarity to the binding site of other metalloproteinases. Batroxase presented weak hemorrhagic activity, with a MHD of 10 mu g, and was able to hydrolyze extracellular matrix components, such as type IV collagen and fibronectin. The toxin cleaves both a and beta-chains of the fibrinogen molecule, and it can be inhibited by EDTA. EGTA and beta-mercaptoethanol. Batroxase was able to dissolve fibrin clots independently of plasminogen activation. These results demonstrate that Batroxase is a zinc-dependent hemorrhagic metalloproteinase with fibrin(ogen)olytic and thrombolytic activity. Published by Elsevier Ltd.

Effect of varicocele on sperm function and semen oxidative stress

OBJECTIVE To assess the effect of varicocele on sperm DNA integrity, mitochondrial activity, lipid peroxidation and acrosome integrity. PATIENTS AND METHODS In all, 30 patients with a clinically diagnosed varicocele of grade II or III and 32 men without a varicocele were evaluated for sperm DNA fragmentation (comet assay), mitochondrial activity (3,3'-diaminobenzidine assay), lipid peroxidation (malondialdehyde) and acrosome integrity (fluorescent probe labelled peanut agglutinin). RESULTS The varicocele group showed fewer spermatozoa with intact DNA (grade II, P = 0.040), more cells with inactive mitochondria (class III, P = 0.001), fewer cells with active mitochondria (class I, P = 0.005) and fewer spermatozoa with intact acrosomes (P < 0.001). Finally, no significant differences were observed in lipid peroxidation levels. CONCLUSION Men with varicocele showed an increase in sperm DNA fragmentation and a reduction in mitochondrial activity and acrosome integrity. However, lipid peroxidation levels remained unchanged.