Globins play a key role in regulating nitric oxide (NO) levels in all forms of life. Five key reactions of NO with mammalian muscle myoglobin (Mb) and red blood cell hemoglobin (Hb) have been examined: (1) reversible NO binding to Fe(II) forms; (2) reversible NO binding to Fe(III) forms; (3) NO dioxygenation by Fe(II)O complexes; (4) autoxidation of Fe(II)NO complexes in the presence of O; and (5) autoreduction of Fe(III)NO complexes. NO reacts rapidly and almost irreversibly with deoxyMb(FeII) in the absence of O, whereas it reacts much more slowly and weakly with metMb(FeIII).
View Article and Find Full Text PDFThe ligand binding properties and resistances to denaturation of >300 different site-directed mutants of sperm whale, pig, and human myoglobin have been examined over the past 15 years. This library of recombinant proteins has been used to derive chemical mechanisms for ligand binding and to examine the factors governing holo- and apoglobin stability. We have also examined the effects of mutagenesis on the dioxygenation of NO by MbO(2) to form NO(3)(-) and metMb.
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