Redox Function of Tetrahydrobiopterin and Effect ofl-Arginine on Oxygen Binding in Endothelial Nitric Oxide Synthase†

Biochemistry ◽  
2004 ◽  
Vol 43 (41) ◽  
pp. 13137-13148 ◽  
Author(s):  
Vladimir Berka ◽  
Hui-Chun Yeh ◽  
De Gao ◽  
Farheen Kiran ◽  
Ah-Lim Tsai
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Oxygen Binding ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

scholarly journals Evidence of Two Distinct Oxygen Complexes of Reduced Endothelial Nitric Oxide Synthase

2004 ◽  
Vol 279 (19) ◽  
pp. 19824-19831 ◽  
Author(s):  
Stéphane Marchal ◽  
Antonius C. F. Gorren ◽  
Morten Sørlie ◽  
K. Kristoffer Andersson ◽  
Bernd Mayer ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Distinct Species ◽  
Electronic Configuration ◽  
Product Formation ◽  
Oxygen Binding ◽  
Oxygenase Domain ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Oxygen binding to the oxygenase domain of reduced endothelial nitric oxide synthase (eNOS) results in two distinct species differing in their Soret and visible absorbance maxima and in their capacity to exchange oxygen by CO. At 7 °C, heme-oxy I (with maxima at 420 and 560 nm) is formed very rapidly (kon≈ 2.5·106m–1·s–1) in the absence of substrate but in the presence of pterin cofactor. It is capable of exchanging oxygen with CO at –30 °C. Heme-oxy II is formed more slowly (kon≈ 3·105m–1·s–1) in the presence of substrate, regardless of the presence of pterin. It is also formed in the absence of both substrate and pterin. In contrast to heme-oxy I, it cannot exchange oxygen with CO at cryogenic temperature. In the presence of arginine, heme-oxy II is characterized by absorbance maxima near 432, 564, and 597 nm. When arginine is replaced byN-hydroxyarginine, and also in the absence of both substrate and pterin, its absorbance maxima are blue-shifted to 428, 560, and 593 nm. Heme-oxy I seems to resemble the ferrous dioxygen complex observed in many hemoproteins, including cytochrome P450. Heme-oxy II, which is the oxygen complex competent for product formation, appears to represent a distinct conformation in which the electronic configuration is essentially locked in the ferric superoxide complex.

Localization of endothelial nitric oxide synthase in the normal and failing human atrial myocardium

1996 ◽  
Vol 54 ◽  
pp. 786-787
Author(s):  
Chi-Ming Wei ◽  
Margarita Bracamonte ◽  
Shi-Wen Jiang ◽  
Richard C. Daly ◽  
Christopher G.A. McGregor ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Heart Failure ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Cardiac Tissues ◽  
Mammalian Tissues ◽  
End Stage Heart Failure ◽  
End Stage ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Nitric oxide (NO) is a potent endothelium-derived relaxing factor which also may modulate cardiomyocyte inotropism and growth via increasing cGMP. While endothelial nitric oxide synthase (eNOS) isoforms have been detected in non-human mammalian tissues, expression and localization of eNOS in the normal and failing human myocardium are poorly defined. Therefore, the present study was designed to investigate eNOS in human cardiac tissues in the presence and absence of congestive heart failure (CHF).Normal and failing atrial tissue were obtained from six cardiac donors and six end-stage heart failure patients undergoing primary cardiac transplantation. ENOS protein expression and localization was investigated utilizing Western blot analysis and immunohistochemical staining with the polyclonal rabbit antibody to eNOS (Transduction Laboratories, Lexington, Kentucky).

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