The development of a new instrument capable of mixing reagents and measuring reactions down to 4 �s has enabled us to monitor the initial events in the reaction between nitric oxide and oxy-myoglobin (Mb-O2). Based on previous experiments (1-2) Scheme 1 was proposed that also includes our preliminary kinetic results. After initial formation of MbFeIII-OONO- the reactions up to the MbFeIII-nitrato complex are completed within 6 �s. The results suggest that the peroxynitrite intermediate is not a source of its unbound toxic form, but the ~ 5% �  NO2that escapes is.                                       The CuA-containing NOR from Bacillus azotoformans (qCuANOR) accepts electrons from cyt. c551 and MQH2 (3). NO is reduced by heme-Fe-�FeB binuclear center. The qCuANOR subunit I is 77% homologous to the recently crystalized Geobacillus stearothermophilusqNOR (4). Freeze-quench UV-Vis studies show two NO binding phases with different spectral characteristics after 100 and 400 �s followed by complete oxidation in 10 ms. Additional functional studies are interpreted in terms of the structure of qNOR.1. Y Matsumoto, T. Tosha, AV Pisliakov, T Hino, H Sugimoto, S Nagano, Y Sugita, Y Shiro Nat Struct Mol Biol 19 , 238-245 (2012).2. ET Yukl, S de Vries, P Moenne-Loccoz J Am Chem Soc 131 , 7234-7235 (2009).3. J. Su, JT Groves J Am Chem Soc 131 , 12979-12988 (2009).4. Suharti, MJF Strampraad, I. Schroder, S de Vries Biochemistry 40 , 2632-2639 (2001).

Nitric oxide and its reactions with myoglobin and NO reductase

248th National Meeting (2014)

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