Isolation and characterization of Bradykinin potentiating peptides from Agkistrodon bilineatus venom.

BACKGROUND: Snake venom is a source of many pharmacologically important molecules. Agkistrodon bilineatus commonly known as Cantil, is spread over Central America particularly in Mexico and Costa Rica. From the venom of Agkistrodon bilineatus we have isolated and characterised six hypotensive peptides, and two bradykinin inhibitor peptides. The IC-50 value of four synthesized peptides was studied, towards angiotensin converting enzyme, in order to study the structure-function relationship of these peptides. RESULTS: The purification of the peptides was carried out by size exclusion chromatography, followed by reverse phase chromatography. Sequences of all peptides were determined applying MALDI-TOF/TOF mass spectrometry. These hypotensive peptides bear homology to bradykinin potentiating peptides and venom vasodilator peptide. The peptide with m/z 1355.53 (M + H)(+1), and the corresponding sequence ZQWAQGRAPHPP, we identified for the first time. A precursor protein containing a fragment of this peptide was reported at genome level, (Uniprot ID P68515), in Bothrops insularis venom gland. These proline rich hypotensive peptides or bradykinin potentiating peptides are usually present in the venom of Crotalinae, and exhibit specificity in binding to the C domain of somatic angiotensin converting enzyme. Four of these hypotensive peptides, were selected and synthesized to obtain the required quantity to study their IC50 values in complex with the angiotensin converting enzyme. The peptide with the sequence ZLWPRPQIPP displayed the lowest IC50 value of 0.64 µM. The IC50 value of the peptide ZQWAQGRAPHPP was 3.63 µM. CONCLUSION: The canonical snake venom BPPs classically display the IPP motif at the C-terminus. Our data suggest that the replacement of the highly conserved hydrophobic isoleucine by histidine does not affect the inhibitory activity, indicating that isoleucine is not mandatory to inhibit the angiotensin converting enzyme. The evaluation of IC 50 values show that the peptide with basic pI value exhibits a lower IC 50 value.

Oxide Derived Copper for Electrochemical Reduction of CO2 to C2+ Products.

The electrochemical reduction of carbon dioxide (CO2) on copper electrode derived from cupric oxide (CuO), named oxide derived copper (ODCu), was studied thoroughly in the potential range of -1.0 V to -1.5 V versus RHE. The CuO nanoparticles were prepared by the hydrothermal method. The ODCu electrode was used for carbon dioxide reduction and the results revealed that this electrode is highly selective for C2+ products with enhanced current density at significantly less overpotential. This catalyst shifts the selectivity towards C2+ products with the highest Faradaic efficiency up to 58% at -0.95 V. In addition, C2 product formation at the lowest onset potential of -0.1 V is achieved with the proposed catalyst. X-ray diffraction and scanning electron microscopy revealed the reduction of CuO to Cu (111) nanoparticles during the CO2 RR. The intrinsic property of the synthesized catalyst and its surface reduction are suggested to induce sites or edges for facilitating the dimerization and coupling of intermediates to ethanol and ethylene.