Methanosarcina acetivorans is a strictly anaerobic non-motile methane-producing Archaea expressing protoglobin (Pgb) which might either facilitate O(2) detoxification or act as a CO sensor/supplier in methanogenesis. Unusually, M. acetivorans Pgb (MaPgb) binds preferentially O(2) rather than CO and displays anticooperativity in ligand binding. Here, kinetics and/or thermodynamics of ferric and ferrous MaPgb (MaPgb(III) and MaPgb(II), respectively) nitrosylation are reported. Data were obtained between pH 7.2 and 9.5, at 22.0 °C. Addition of NO to MaPgb(III) leads to the transient formation of MaPgb(III)-NO in equilibrium with MaPgb(II)-NO(+). In turn, MaPgb(II)-NO(+) is converted to MaPgb(II) by OH(-)-based catalysis. Then, MaPgb(II) binds NO very rapidly leading to MaPgb(II)-NO. The rate-limiting step for reductive nitrosylation of MaPgb(III) is represented by the OH(-)-mediated reduction of MaPgb(II)-NO(+) to MaPgb(II). Present results highlight the potential role of MaPgb in scavenging of reactive nitrogen and oxygen species.
|Titolo:||Reductive nitrosylation of Methanosarcina acetivorans protoglobin : a comparative study|
|Parole Chiave:||Methanosarcina acetivorans protoglobin ; Reductive nitrosylation of ferric ; Methanosarcina acetivorans protoglobin ; Nitrosylation of ferrous Methanosarcina acetivorans protoglobin ; Kinetics ; Thermodynamics|
|Settore Scientifico Disciplinare:||Settore BIO/10 - Biochimica|
|Data di pubblicazione:||25-gen-2013|
|Digital Object Identifier (DOI):||10.1016/j.bbrc.2012.11.122|
|Appare nelle tipologie:||01 - Articolo su periodico|