title: Inhibition of pseudoperoxiadse activity of human red blood cell hemoglobin by methocarbamol.
abstract: After red blood cells lysis, hemoglobin is released to blood circulation. Hemoglobin is carried in blood by binding to haptoglobin. In normal individuals, no free hemoglobin is observed in the blood, because most of the hemoglobin is in the form of haptoglobin complex. In some diseases that are accompanied by hemolysis, the amount of released hemoglobin is higher than its complementary haptoglobin. As a result, free hemoglobin appears in the blood, which is a toxic compound for these patients and may cause renal failure, hypertensive response and risk of atherogenesis. Free hemoglobin has been determined to have peroxidase activity and considered a pseudoenzyme. In this study, the effect of methocarbamol on the peroxidase activity of human hemoglobin was investigated. Our results showed that the drug inhibited the pseudoenzyme by un-competitive inhibition. Both Kmand Vmaxdecreased by increasing the drug concentration. Kiand IC50values were determined as 6 and 10mM, respectively. Docking results demonstrated that methocarbamol did not attach to heme group directly. A hydrogen bond linked NH2of carbamate group of methocarbamol to the carboxyl group of Asp126 side chain. Two other hydrogen bonds could be also observed between hydroxyl group of the drug and Ser102 and Ser133 residues of the pseudoenzyme.
authors.affiliation: BioResearch Lab, Faculty of Biological Sciences, Shahid Beheshti University, G.C., Iran. Electronic address: d_mtehrani@sbu.ac.ir.
authors.forename: Dariush
authors.initials: D
authors.lastname: Minai-Tehrani
authors.affiliation: Department of Pharmacology & Toxicology, Pharmaceutical Sciences Branch, Islamic Azad University (IAUPS), Tehran, Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Toofani
authors.affiliation: Department of Pharmacology & Toxicology, Pharmaceutical Sciences Branch, Islamic Azad University (IAUPS), Tehran, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Yazdi
authors.affiliation: Nanobiotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
authors.forename: Arash
authors.initials: A
authors.lastname: Minai-Tehrani
authors.affiliation: Protein Research Center, Shahid Beheshti University, G.C., Tehran, Iran.
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Mollasalehi
authors.affiliation: Faculty of Science, York University, Toronto, Canada.
authors.forename: Kourosh
authors.initials: K
authors.lastname: Bakhtiari Ziabari
mesh_terms: D001665:Binding Sites; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000737:chemistry*; D004912:Erythrocytes / Q000737:chemistry / Q000201:enzymology*; D005914:Globins / Q000737:chemistry; D006418:Heme / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry*; D006461:Hemolysis; D006801:Humans; D006860:Hydrogen Bonding; D007700:Kinetics; D008721:Methocarbamol / Q000737:chemistry*; D062105:Molecular Docking Simulation; D009125:Muscle Relaxants, Central / Q000737:chemistry*; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013816:Thermodynamics
chemical_list: D004791:Enzyme Inhibitors; D006454:Hemoglobins; D009125:Muscle Relaxants, Central; D008721:Methocarbamol; D006418:Heme; D005914:Globins; D009195:Peroxidase
keywords: Hemoglobin; Human erythrocyte; Inhibition; Methocarbamol; Pseudoperoxidase