Magnetic Circular Dichroism Spectroscopy as a Probe of Ferric Cytochrome P-450 and its Ligand Complexes

Nitric oxide interaction with insect nitrophorins and thoughts on the electron configuration of the FeNO complex

“…Spectroscopic techniques that have been utilized to characterize nitrosylheme proteins include magnetic circular dichroism (MCD) [168,169], infrared (IR) [134,[170][171][172][173][174], resonance Raman (RR) [43,[175][176][177][178][179][180], Mössbauer [181][182][183][184][185], and EPR spectroscopies [61,134,150,[186][187][188][189][190][191][192][193][194][195][196][197][198][199][200]. MCD has been used to characterize the protein-provided axial ligand bound to both Fe(II) and Fe(III) forms of various heme proteins, using the NO, CO, phosphine, and other adducts to develop MCD spectra that are unique for the fifth (protein-provided) ligand [168,169].…”

The Extracellular Heme-binding Protein HbpS from the Soil Bacterium Streptomyces reticuli Is an Aquo-cobalamin Binder

“…Hemin was dissolved in 100 mM NaOH, and its concentration was determined using ⑀ 385 ϭ 58.4 mM Ϫ1 cm Ϫ1 (36). Fresh dilutions were always made using 10 mM NaOH.…”

CO and NO bind to Fe(II) DiGeorge critical region 8 heme but do not restore primary microRNA processing activity

“…The Soret maximum is not near 450 nm; therefore, neither of the two cysteine thiolates bound to Fe(III) Rhed are retained in the Fe(II) state [45]. Furthermore, the fact that there is no pH-dependent shift of the Soret maximum to 450 nm with increasing pH rules out a cysteine thiolate, with an expected pK a ≤8 [46], as the protonatable sixth ligand.…”

“…The spectral positions and intensities are consistent with a 6cLS Fe(II)-CO species with a neutral ligand trans to the CO. The 420 nm Soret band rules out the presence of a cysteine thiolate trans to CO; a thiolate-bound Fe(II)-CO species would exhibit a Soret band near 450 nm [22,45,58]. Furthermore, the spectral similarity between Fe(II)-CO SeMet Rhed and the wild-type protein eliminates methionine as a possible ligand (Table S1).…”