Characterization of the Mechanism and Magnitude of Cytoglobin-mediated Nitrite Reduction and Nitric Oxide Generation under Anaerobic Conditions

Abstract

Background: Cytoglobin plays cytoprotective roles under hypoxic/ischemic conditions, but the mechanisms remain unclear. Results: Cytoglobin functions as a nitrite reductase leading to NO generation and soluble guanylyl cyclase activation under anaerobic or severely hypoxic conditions and this is increased by acidosis as occurs in ischemia. Conclusion: Cytoglobin-mediated nitrite reduction generates NO that activates soluble guanylyl cyclase under hypoxic/ischemic conditions. Significance: Cytoglobin serves a protective function by reducing nitrite to NO under ischemic conditions.

NO2−-mediated nitrosylation of ferrous microperoxidase-11

“…to a single-exponential decay for more than 91 ± 7% and 88 ± 6% of their courses, respectively, corresponding to 46 ± 4% and 44 ± 4%, respectively, of the theoretical total amplitude (= 100%). Therefore, 0°C, as previously reported for nonsymbiotic hemoglobins from Arabidopsis thaliana, human cytoglobin, and human neuroglobin [25][26][27]. On the other hand, the ferric derivative has been reported to be the main product of the reaction of ferrous mouse neuroglobin with NO 2 − , the ferrous nitrosylated species being formed only transiently and at low levels (b20%) [24].…”

“…The primary finding of this study is to highlight the role played by the coordination geometry of the heme-Fe(II) atom, the structural features of the heme cavity and/or the arrangement of barriers along the ligand pathway toward the heme pocket in the modulation of the NO 2 − reduction to NO by heme-proteins and related heme-model compounds with the concomitant formation of the ferrous nitrosylated derivative (Table 1) [21,[25][26][27]30,31,[34][35][36][37]39]. In this respect, MP-11-Fe represents a valuable heme-model compound displaying the pentacoordinated metal center instead of the hexa-coordinated heme-Featom of the parent horse heart cyt c [22].…”

“…Kinetics and thermodynamics of the NO 2 − -mediated nitrosylation of MP11-Fe(II) were analyzed in the framework of the minimum reaction mechanism depicted in Scheme 1 [21,[24][25][26][27][29][30][31][32][33][34][35][36][37][38][39].…”

“…The time-dependent changes of MP11-Fe(II), MP11-Fe(III), and/or MP11-Fe(II)-NO were analyzed by the MatLab program (The Math Works Inc., Natick, MA, USA) using the absorbance spectra of ferrous deoxygenated (λ max = 414 nm and ε 414 nm = 1.03 × 10 5 M −1 cm −1 ), ferric (λ max = 395 nm and ε 395 nm = 1.23 × 10 5 M −1 cm −1 ), and ferrous nitrosylated (λ max = 410 nm and ε 410 nm = 1.18 × 10 5 M −1 cm −1 ) MP11-Fe species as references [24][25][26][27]. The results are given as mean values of at least four experiments plus or minus the corresponding standard deviation.…”

Luteolinidin Protects the Postischemic Heart through CD38 Inhibition with Preservation of NAD(P)(H)

“…Isolated hearts subjected to control treatment, I/R with the empty liposome vehicle control, and I/R with luteolinidin treatment were assayed for cGMP content (Li et al, 2012). At the end of each protocol, hearts were treated with 1 mM acetylcholine to determine the ability of eNOS to increase cGMP.…”