Specificity of Glutathione S-Transferases in the Glutathione Conjugation of Carcinogenic Diol Epoxides

2006 ◽  
pp. 103-128
Author(s):  
Hui Xiao ◽  
Shivendra Singh
Keyword(s):  
Glutathione Conjugation ◽  
Diol Epoxides ◽  
Glutathione S Transferases

scholarly journals The hypothalamic–hypophyseal–gonadal regulation of hepatic glutathione S-transferases in the rat

1981 ◽  
Vol 198 (1) ◽  
pp. 211-217 ◽  
Author(s):  
Coral A. Lamartiniere
Keyword(s):  
Adult Male ◽  
Sexual Differentiation ◽  
Male Rats ◽  
Adult Males ◽  
Glutathione S Transferase ◽  
Glutathione Conjugation ◽  
Inhibiting Factor ◽  
Hepatic Glutathione ◽  
Hypophysectomized Rats ◽  
Glutathione S Transferases

Hepatic glutathione S-transferase activities were determined with the substrates 1,2-dichloro-4-nitrobenzene and 1-chloro-2,4-dinitrobenzene. Sexual differentiation of glutathione S-transferase activities is not evident during the prepubertal period, but glutathione conjugation with 1,2-dichloro-4-nitrobenzene is 2–3-fold greater in adult males than in females. Glutathione conjugation with 1-chloro-2,4-dinitrobenzene is slightly higher in adult males than adult females. No change in activity was observed after postpubertal gonadectomy of males or females. Neonatal castration of males results in a significant decrease in glutathione conjugation with 1,2-dichloro-4-nitrobenzene. Hypophysectomy, or hypophysectomy followed by gonadectomy did result in significantly higher glutathione S-transferase activities in both sexes. These increases can be reversed by implanting an adult male or female pituitary or four prepubertal pituitaries under the kidney capsule. Postpubertal sexual differentiation of glutathione S-transferase activities is neither dependent on pituitary sexual differentiation nor pituitary maturation. Prolactin concentrations are inversely related to glutathione S-transferase activities in hypophysectomized rats with or without ectopic pituitaries. Somatotropin exogenously administered to hypophysectomized rats results in decreased glutathione S-transferase activities, whereas prolactin has no effect. Adult male rats treated neonatally with monosodium l-glutamate to induce arcuate nucleus lesions of the hypothalamus have decreased glutathione S-transferase activities towards 1,2-dichloro-4-nitrobenzene and decreased somatotropin concentrations. Our experiments suggests that sexual differentiation of hepatic glutathione S-transferase is a result of a hypothalamic inhibiting factor in the male (absent in the female). This postpubertally expressed inhibiting factor acts on the pituitary to prevent secretion of a pituitary inhibiting factor (autonomously secreted by the female), resulting in higher glutathione S-transferase activities in the adult male than the adult female.

Glutathione conjugation of aflatoxin B1 exo- and endo-epoxides by rat and human glutathione S-transferases

1992 ◽  
Vol 5 (4) ◽  
pp. 470-478 ◽  
Author(s):  
Kevin D. Raney ◽  
David J. Meyer ◽  
Brian Ketterer ◽  
Thomas M. Harris ◽  
F. Peter Guengerich
Keyword(s):  
Aflatoxin B1 ◽  
Glutathione Conjugation ◽  
Glutathione S Transferases

Visualization of Glutathione Conjugation and Inducibility of Glutathione S-Transferases in Onion {Allium cepa L.) Epidermal Tissue

1999 ◽  
Vol 54 (12) ◽  
pp. 1033-1041 ◽  
Author(s):  
Peter Schröder ◽  
Andreas Stampfl
Keyword(s):  
Enzyme Activity ◽  
Allium Cepa ◽  
Signal Molecules ◽  
Enzymatic Cleavage ◽  
Glutathione Conjugation ◽  
Glutathione Conjugates ◽  
Epidermal Tissue ◽  
Allium Cepa L ◽  
Glutathione S Transferases ◽  
Gst Activity

Glutathione conjugation of 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, NBD-Cl, monobromobimane and monochlorobimane was found to occur in epidermal tissue of onion bulbs (Allium cepa L.). Conjugation required the presence of glutathione S-transferases (GST). In order to follow glutathione conjugation microscopically, bimanes were utilized. Monochlorobimane was converted to a brightly fluorescing conjugate that was shown to be transported to the nucleus before sequestration in the vacuole occurred. GST activity was stimulated as well as induced by several electrophilic xenobiotics, by cycloheximide and by several glutathione conjugates. γ-Glutamylcysteine conjugates that are formed during enzymatic cleavage of glutathione conjugates in plants, were not active as inducers of enzyme activity. In the light of the stimulating effects of xenobiotic glutathione conjugates on GST activity, it is concluded that glutathione conjugates may act as signal molecules.

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