Acceleration of Anaerobic Cysteine Transformations to Sulfane Sulfur Consequent to γ-Glutamyl Transpeptidase Inhibition

Toxicity of drugs and radiation in the cells is largely dependent on the level of thiols. In the present studies, an attempt has been made to inhibit γ-glutamyl transpeptidase (γGT) activity in EAT-bearing animals tissue. We have expected that administration of γGT inhibitors: acivicin and 1,2,3,4-tetrahydroisoquinoline (TIQ) may influence GSH/γ–glutamyl transpeptidase (γGT) system in the regulation of cysteine concentration and anaerobic cysteine metabolism in normal and cancer cells. Development of Ehrlich ascites tumor in mice enhances peroxidative processes, diminishes levels of nonprotein thiols (NPSH) and sulfane sulfur, and lowers activities of enzymes involved in its formation and transfer in the liver and kidney. Although γGT inhibitors further decrease NPSH level, they increase cysteine and sulfane sulfur levels. This means that upon γGT inhibition, cysteine can be efficiently acquired by normal liver and kidney cells via another pathway, that is so productive that sulfane sulfur level and intensity of anaerobic cysteine metabolism even rise.