Khadega Khamis Moh Alazoumi, Anwar Ahmed, Salman Freeh Alamery, Anas Shamsi, Basir Ahmad, Asimul Islam* and Humaira Farooqi* Pages 31 - 42 ( 12 )
Background: The exposure to heavy metals due to unrestrained industrialization, pollution and non-degradability imposes a significant risk to human health. Proteins are prime targets of heavy metal stress, however, the underlying mechanisms and its impact on heme proteins is still not entirely clear.Objective: To analyze the deleterious effect of heavy metals such as cadmium, chromium and mercury on conformation of two proteins namely, cytochrome c and myoglobin. The protective effect of glycine and ascorbic acid (animal origin), gallic acid and sesamol (plant origin) on heavy metal exposure was studied. Methods: Far- and near-UV Circular Dichroism (CD) measurements monitored the changes in secondary and tertiary structure. Absorption Soret spectroscopy study revealed changes in heme-protein interaction. Peroxidase activity has been assayed to measure the absorption of tetraguaiacol. The interaction of heme proteins with different heavy metals was done using docking study. Result: Far- and near-UV CD measurements reveal that heavy metals disrupt the secondary and tertiary structure of heme proteins. Antioxidants counteract the deleterious effect of heavy metals. Absorption spectroscopy revealed changes in the Soret region of these heme proteins. Changes in peroxidase activity was observed on addition of heavy metals and antioxidants. Molecular docking validated interaction of the heavy metals with proteins with a significant binding affinity (-2.3 kcal/- mol). Conclusion: Heavy metals interfered and disrupted both the heme proteins and mercury showed the maximum deleterious effect, further, chromium showed detrimental effect at very small concentration. The antioxidants from animal origin exhibited better protective response than those from plant source.
Cytochrome c, myoglobin, heavy metals, protein structure, protein denaturation, antioxidants.
Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi-110062, Center of Excellence in Biotechnology Research, Department of Biochemistry, College of Science, King Saud University, Riyadh, Protein Research Chair, Department of Biochemistry, College of Science, King Saud University, Riyadh, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi-110025, Institute of Molecular Medicine, Jamia Hamdard, New Delhi-110062, Institute of Molecular Medicine, Jamia Hamdard, New Delhi- 110062, Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi-110062