Cell-mediated biotransformation of S-nitrosoglutathione.
Spontaneous release of nitric oxide (NO) from S-nitrosothiols cannot explain their bioactivity, suggesting a role for cellular metabolism or receptors. Using immortalised cells and human platelets, we have identified a cell-mediated mechanism for the biotransformation of the physiological S-nitrosothiol compound S-nitrosoglutathione (GSNO) into nitrite. We suggest the name "GSNO lyase" for this activity. GSNO lyase activity varied between cell types, being highest in a fibroblast cell line and lowest in platelets. In NRK 49F fibroblasts, GSNO lyase mediated a saturable, GSNO concentration-dependent accumulation of nitrite in conditioned medium, which was inhibited both by transition metal chelators, and by subjecting cells to oxidative stress using a combination of the thiol oxidant diamide and Zn2+, a glutathione reductase inhibitor. Activity was resistant, however, to both acivicin, an inhibitor of gamma-glutamyl transpeptidase (EC 2.3.2.2), and to ethacrynic acid, an inhibitor of Pi class glutathione-S-transferases (EC 2.5.1.18), thus neither of these enzymes could account for NO release. Although GSNO lyase does not explain the platelet-selective pharmacological properties of GSNO, cellular biotransformation suggests therapeutic avenues for targeted delivery of NO to other tissues.
Gordge
M P
MP
Institute of Urology and Nephrology, University College London, UK.
Addis
P
P
Noronha-Dutra
A A
AA
Hothersall
J S
JS
D000818:Animals; D001711:Biotransformation; D002460:Cell Line; D002614:Chelating Agents / Q000494:pharmacology; D017077:Culture Media, Conditioned; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics; D006706:Homeostasis; D006801:Humans; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D009603:Nitroso Compounds / Q000378:metabolism / Q000493:pharmacokinetics*; D051381:Rats; D026422:S-Nitrosoglutathione; D013552:Swine
D002614:Chelating Agents; D017077:Culture Media, Conditioned; D009566:Nitrates; D009573:Nitrites; D009603:Nitroso Compounds; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D005978:Glutathione