TY - JOUR
T1 - 14N-Spin trapping of free radicals in the presence of 15N-spin labeled Neisseria gonorrhoeae
AU - Rosen, Gerald M.
AU - Pou, Sovitj
AU - Cohen, Myron S.
AU - Hassett, Daniel J.
AU - Britigan, Bradley E.
AU - Barber, Michael J.
AU - Cao, Guan Liang
AU - Cosby, Kennyatta
AU - Sturgeon, Bradley E.
AU - Halpern, Howard J.
PY - 1999/2
Y1 - 1999/2
N2 - One of the difficult tasks confronting the study of free radicals in biology is the inability to measure "on line" injury to a biological target, while characterizing the reactive species responsible for the toxic event. This is particularly relevant in light of the fact that specific free radicals play a critical role in host immune response. An approach towards addressing this important issue draws upon the unique EPR spectral properties of 14N/15N-labeled compounds. In particular, Neisseria gonorrhoeae has been covalently labeled with 15N-deuterium17-containing 4-maleimido-2,2,6,6-tetramethylpiperidin-1-yloxyl (15N-D17-4-MAL-TEMPO). The EPR spectrum from bacteria so labeled exhibited two low-field peaks: (a) a broad, strongly immobilized species classified as "S"; (b) a more narrow, weakly immobilized component termed "W". The W/S ratio is an indicator of changes in membrane organization. In the presence of the superoxide-generating system, hypoxanthine/xanthine oxidase, an increase in the W/S ratio from 3.3 for control to 6.4 was observed, which was only partially inhibited by superoxide dismutase (W/S ratio of 4.4). When the spin trap 5,5-dimethyl-1-pyrroline 14N-oxide (DMPO) was included in the above reaction mixture, an EPR spectrum was recorded, which was a composite of 2,2,-dimethyl-5-hydroperoxypyrrolidin-1-yl-14N-oxyl (DMPO-OOH) and 15N-D17-4-MAL-TEMPO-labeled Neisseria gonorrhoeae. With the use of computer subtraction procedures, the W/S ratio was found to be 6.4. The experiments demonstrate the utility of 14N/15N-labeled aminoxyls as a valuable tool in accessing the effects of specific free radicals on the fluidity of cell membranes.
AB - One of the difficult tasks confronting the study of free radicals in biology is the inability to measure "on line" injury to a biological target, while characterizing the reactive species responsible for the toxic event. This is particularly relevant in light of the fact that specific free radicals play a critical role in host immune response. An approach towards addressing this important issue draws upon the unique EPR spectral properties of 14N/15N-labeled compounds. In particular, Neisseria gonorrhoeae has been covalently labeled with 15N-deuterium17-containing 4-maleimido-2,2,6,6-tetramethylpiperidin-1-yloxyl (15N-D17-4-MAL-TEMPO). The EPR spectrum from bacteria so labeled exhibited two low-field peaks: (a) a broad, strongly immobilized species classified as "S"; (b) a more narrow, weakly immobilized component termed "W". The W/S ratio is an indicator of changes in membrane organization. In the presence of the superoxide-generating system, hypoxanthine/xanthine oxidase, an increase in the W/S ratio from 3.3 for control to 6.4 was observed, which was only partially inhibited by superoxide dismutase (W/S ratio of 4.4). When the spin trap 5,5-dimethyl-1-pyrroline 14N-oxide (DMPO) was included in the above reaction mixture, an EPR spectrum was recorded, which was a composite of 2,2,-dimethyl-5-hydroperoxypyrrolidin-1-yl-14N-oxyl (DMPO-OOH) and 15N-D17-4-MAL-TEMPO-labeled Neisseria gonorrhoeae. With the use of computer subtraction procedures, the W/S ratio was found to be 6.4. The experiments demonstrate the utility of 14N/15N-labeled aminoxyls as a valuable tool in accessing the effects of specific free radicals on the fluidity of cell membranes.
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U2 - 10.1039/a806100i
DO - 10.1039/a806100i
M3 - Article
AN - SCOPUS:0042225707
SP - 297
EP - 300
JO - Journal of the Chemical Society, Perkin Transactions 2
JF - Journal of the Chemical Society, Perkin Transactions 2
SN - 1470-1820
IS - 2
ER -