Carbon Monoxide-releasing Molecule-3 (CORM-3; Ru(CO)3Cl(Glycinate)) as a Tool to Study the Concerted Effects of Carbon Monoxide and Nitric Oxide on Bacterial Flavohemoglobin Hmp

Abstract

Background: CO-releasing molecules (CO-RMs) are used to study biological interactions with this toxic gas. Results: CORM-3 inhibits the NO detoxification activity of the E. coli flavohemoglobin Hmp in vivo but not in vitro. Conclusion: CO-RMs must be used with regard to their chemistry in biological studies. Significance: CORM-3 is a useful tool to study concerted effects of NO and CO in vivo.

CO-releasing Metal Carbonyl Compounds as Antimicrobial Agents in the Post-antibiotic Era

“…Thus, in biological situations where dithionite (or sulfite, metabisulfite, or perhaps other species) are absent, the myoglobin assay overestimates the rate of CO release. Likewise, CORM-3 does not release CO to the purified flavohemoglobin (Hmp) when reduced with NADH but does so in the presence of dithionite ( 45 ). These findings probably explain the discrepancy noted between the myoglobin assay and the CO electrode ( 22 ), previously attributed to the need for certain CORMs to interact “with biological components to trigger the release of CO” ( 22 ).…”

“…An alternative assay that obviates the need for dithionite uses oxyhemoglobin ( 43 ). Such globin assays could in principle be applied to CO assays within bacteria; indeed Escherichia coli Hmp expressed at high copy number is a sensitive monitor of CO liberated inside bacteria from CORMs ( 45 ).…”

“…Refs. 21 , 45 , and 82 ), and functionally distinct oxidases have differential sensitivities to CORMs ( 85 ), inhibition of respiration is not the only factor affecting the bactericidal activity of CORMs ( 22 ). CORMs may be toxic under anoxic conditions in the absence of respiration ( 16 , 20 , 21 ).…”

Kinetic Analysis and Structural Interpretation of Competitive Ligand Binding for NO Dioxygenation in Truncated Hemoglobin N

“…13,14 However, the two ligands also work in concert, specifically in the NO dioxygenation reaction where harmful nitric oxide is converted to benign nitrate to relieve nitrosative stress in bacteria 15 and is relevant for NO-detoxification in blood. [16][17][18][19] NO dioxygenation is essential for flavohemoglobins and truncated hemoglobins in bacteria as well as myoglobin and hemoglobin in mammals. 20 The reaction was first studied for Myoglobin (Mb) 21 followed by studies focusing on nitrate formation in other globins using experimental and computational approaches.…”

Reactive molecular dynamics: From small molecules to proteins

“…Competitive ligand binding in truncated hemoglobin N MS-ARMD with conventional force fields was recently also applied to the competitive rebinding of NO and O 2 in the active site of truncated Hemoglobin N (trHbN). 191 The dioxygenation reaction converts harmful nitric oxide to benign nitrate in bacteria 192 and is relevant for NO-detoxification in blood [193][194][195][196] The reaction was first studied for Myoglobin (Mb) 197 followed by studies focusing on nitrate formation in other globins using experimental and computational approaches. [198][199][200][201] From stopped flow experiments, the second-order rate constants for the reaction of NO with oxyHb and oxyMb (process III, see Equation (19)) are 4.36 × 10 7 and 8.9 × 10 7 M −1 s −1 , respectively.…”