Formation of nitrosothiols from gaseous nitric oxide at pH 7.4.
Nitric oxide (NO) is generated in biological systems and plays important roles as a regulatory molecule. Its ability to bind to haem iron is well known. Moreover, it may lose an electron, forming the nitrosonium ion, involved in the synthesis of S-nitrosothiols (SNOs). It has been suggested that S-nitrosohaemoglobin (-SNO Hb) and low molecular weight SNOs may act as reservoirs of NO. SNOs are formed in vitro, at strongly acidic pH values; however, the mechanism of their formation at neutral pH values is still debated. In this paper we report the anaerobic formation of SNOs (both high- and low-molecular weight) from low concentrations of NO at pH 7.4, provided Hb is also present. We propose a reaction mechanism entailing the participation of Fehaem in the formation of NO(+) and the transfer of NO(+) either to Cysbeta(93) of Hb or to glutathione; we show that this reaction also occurs in human RBCs.
Dipartimento di Scienze Biochimiche e Biotecnologie Molecolari, Via del Giochetto, Perugia, Italy. crlpal@unipg.it
Carlo Alberto
CA
Palmerini
Carla
C
Saccardi
Giuseppe
G
Arienti
Roberto
R
Palombari
D000818:Animals; D015374:Biosensing Techniques; D004563:Electrochemistry / Q000379:methods; D004912:Erythrocytes / Q000378:metabolism; D005978:Glutathione / Q000097:blood / Q000737:chemistry; D006454:Hemoglobins / Q000032:analysis / Q000737:chemistry*; D006736:Horses; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009569:Nitric Oxide / Q000737:chemistry*; D026403:S-Nitrosothiols / Q000097:blood / Q000138:chemical synthesis*
D006454:Hemoglobins; D026403:S-Nitrosothiols; C103574:S-nitrosohemoglobin; D009569:Nitric Oxide; D005978:Glutathione