Decreased S-nitrosation of peptide thiols in the membrane interior.
It has been proposed that autoxidation of nitric oxide (()NO) stimulates S-nitrosation of thiols located in the hydrophobic milieu. We tested whether thiols located in hydrophobic membranes undergo enhanced S-nitrosation in the presence of ()NO/O(2). The transmembrane cysteinyl peptides C(4) (AcNH-KKACALA(LA)(6)KK-CONH(2)) and C(8) (AcNH-KKALALACALA(LA)(3)KK-CONH(2)) were incorporated into dilauroylphosphatidylcholine bilayers; their location in the membrane was determined by EPR spin labeling. The peptides, C(8) and C(4), and glutathione (GSH; 300 microM) were treated with a ()NO donor, DEA-NONOate, and nitrosothiol formation was determined under various O(2) levels. Surprisingly, the more hydrophobic cysteinyl peptide, C(8), did not yield any S-nitrosated product compared to GSH in the aqueous phase or C(4) peptide in the liposomes in the presence of ()NO/O(2). These data suggest that thiols located deeply in the hydrophobic core of the membrane may be less likely to undergo S-nitrosation in the presence of ()NO/O(2).
Zhang
Hao
H
Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Andrekopoulos
Christopher
C
Xu
Yingkai
Y
Joseph
Joy
J
Hogg
Neil
N
Feix
Jimmy
J
Kalyanaraman
B
B
D002851:Chromatography, High Pressure Liquid; D008081:Liposomes / Q000737:chemistry*; D008163:Luminescent Measurements; D008567:Membranes, Artificial; D009569:Nitric Oxide / Q000737:chemistry; D009603:Nitroso Compounds / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010455:Peptides / Q000032:analysis / Q000138:chemical synthesis* / Q000302:isolation & purification; D013438:Sulfhydryl Compounds / Q000032:analysis / Q000138:chemical synthesis* / Q000302:isolation & purification; D013997:Time Factors
D008081:Liposomes; D008567:Membranes, Artificial; D009603:Nitroso Compounds; D010455:Peptides; D013438:Sulfhydryl Compounds; D009569:Nitric Oxide; D010100:Oxygen