Electron paramagnetic resonance study of nitrosylhemoglobin and its chemistry in single crystals

Redefining nitric oxide production in legume nodules through complementary insights from electron paramagnetic resonance spectroscopy and specific fluorescent probes

“…In this figure it can also be observed that identical spectra were obtained when Lb 2+ NO was produced from Lb 3+ with an NO donor (DEA) plus dithionite or with NO 2 − plus dithionite. We associated this signal with an electronic spin S =1/2 with principal values of the g tensor g x ~2.07, g y ~2.00, and g z ~1.97, and a partially unresolved hyperfine interaction with one 14 N nucleus; the signal is typical of the heme 2+ -NO species as previously reported for hemoglobin ( Doetschman and Utterback, 1981 ) and cytochrome P-450 ( Tsubaki et al , 1987 ). Moreover, Lb 3+ typically displayed a signal in the 100 mT ( g ~6.0) region, but this signal was noticeable only at low temperatures (<25 K) and could not be detected at 80 K ( Supplementary Fig.…”

Nitrosyl hemoglobin: EPR components at low temperatures

“…2 and 3. A 59 similar temperature and microwave power evolution was also observed in HbNO crystals and it can not be attributed to the broadening of its components (Doetschman and Utterback 1981). To check if both spectral dependences are due to an equilibrium between conformations, we analyse each spectrum as a combination of two component spectra.…”

“…Besides the differences between the two proteins, different temperature ranges are certainly responsible for the different T1 temperature dependence. On the other hand, the saturation measurements (Doetschman and Utterback 1981) in HbNO crystals between 1.6 K and 4.2 K yield lower T 1 and higher T 2 estimates. It is however known that the linewidths in crystals and in solution are considerably different (Brill and Hampton 1979).…”

A novel electrochemical microsensor for the determination of NO and its application to the study of the NO donor S-nitrosoglutathione

“…This indicates that some interaction occurs between NO and certain metal complexes which is similar to that between simple diatomic molecules such as O 2 , CO and certain metal complexes to form their adducts. 21,22 Bioinorganic structures have been demonstrated to be able potentially to mimic metalloenzyme structure and functions. Comparative studies of the functions in both synthetic models and natural systems led to the conclusions that the synthetic models can mimic the activity of cytochrome P-450 families in the case of biomimetic oxidation of hydrocarbons and transportation of oxygen, [23][24][25] and that metalloporphyrins, metallophthalocyanines and metal Schiff bases can be used as biomimetic oxidation catalysts and oxygen carriers such as so-called inorganic enzymes.…”