title: Glutathione, glutathione S-transferase, and transmembrane transport of glutathione conjugate in human neutrophil leukocytes.
abstract: Glutathione (GSH) conjugation is important in the detoxification of carcinogens and other exogenous electrophilic drugs and chemicals. The conjugation is catalyzed by GSH S-transferase. Neutrophil GSH content was 12.3 +/- 2.5 (mean +/- SD) nmol/10(7) cells, and transferase activity of cytosol preparations was 0.187 +/- 0.035 nmol/min/mg protein with 1-chloro-2,4-dinitrobenzene (CDNB) as substrate. Maximal activity was found at a pH of 7.0 and a temperature of 40 degrees C. Apparent Km of transferase was 1.25 +/- 0.18 mmol/L CDNB, and apparent Vmax was 0.621 +/- 0.22 nmol/min/mg. GSH-CDNB conjugate was quantitated by HPLC in cells and in medium after CDNB exposure. Transport of conjugate from cells to medium increased with CDNB concentration to 50 mumol/L, and kinetic data showed two saturable transport mechanisms with apparent Km of 5.90 mumol/L and 0.265 mumol/L, respectively. Cellular GSH content fell rapidly with CDNB concentration greater than 2.5 mumol/L, and was depleted in a 10-minute incubation at a concentration of greater than 50 mumol/L CDNB. Neutrophils have a significant content of GSH and a significant amount of transferase activity, and transport of GSH conjugate involves two distinct saturable pathways. GSH depletion can be accomplished with a relatively low concentration of an exogenous chemical and could impair the ability of the cells to carry out their phagocytic functions.
authors.affiliation: Department of Internal Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0214.
authors.forename: R B
authors.initials: RB
authors.lastname: Scott
authors.forename: S
authors.initials: S
authors.lastname: Matin
authors.forename: S C
authors.initials: SC
authors.lastname: Hamilton
mesh_terms: D000328:Adult; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004137:Dinitrochlorobenzene / Q000378:metabolism*; D004795:Enzyme Stability; D005978:Glutathione / Q000097:blood*; D005982:Glutathione Transferase / Q000097:blood*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009504:Neutrophils / Q000378:metabolism*; D012969:Sodium Fluoride / Q000494:pharmacology; D013696:Temperature
chemical_list: D004137:Dinitrochlorobenzene; D012969:Sodium Fluoride; D005982:Glutathione Transferase; D005978:Glutathione