title: Differences in the reduction kinetics of incorporated spin labels in undifferentiated and differentiated mouse neuroblastoma cells.
abstract: Significant differences in the rate of reduction of two spin labels, 5-doxylstearic acid and TEMPOL, in the undifferentiated and differentiated NB-15 mouse neuroblastoma cells were demonstrated by using electron paramagnetic resonance (EPR) spectroscopy. The half-time (T1/2) values for decay of the EPR signal of 5-doxylstearic acid in the undifferentiated and differentiated neuroblastoma cells were 70 min and 290 min, respectively. The T1/2 values of TEMPOL in the undifferentiated and differentiated cells were 18 min and 34 min, respectively. The cellular reductant was characterized as non-protein-bound sulfhydryl groups. A corresponding difference in the cellular non-protein-bound sulfhydryl content, 19.30 nmol/mg protein for the undifferentiated cells and 6.78 nmol/mg protein for the differentiated cells, was observed. Comparison of the reduction rates of TEMPOL, 5-doxylstearic acid and 16-doxylstearic acid in the undifferentiated NB-15 cells suggested that the permeation of non-protein-bound sulfhydryl compounds from the cytosol to membrane may be responsible for the reduction of the lipid-soluble stearic acid spin labels.
authors.forename: K Y
authors.initials: KY
authors.lastname: Chen
authors.forename: M G
authors.initials: MG
authors.lastname: McLaughlin
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003497:Cyclic N-Oxides / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D006207:Half-Life; D007700:Kinetics; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D010084:Oxidation-Reduction; D013113:Spin Labels; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D003497:Cyclic N-Oxides; D013113:Spin Labels; D013438:Sulfhydryl Compounds; C005072:5-doxylstearic acid; C032363:16-nitroxystearic acid; C001803:tempol