L gsh

L-Cys, D,L-Hcy, L-GSH, and CysGly were purchased from Sigma-Aldrich (St. Louis, MO, USA). Trichloroacetic acid (TCA) was obtained from Wako Pure Chemical (Osaka, Japan). Ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate (SBD-F) was purchased from Dojindo (Kumamoto, Japan). TCEP was purchased from the Tokyo Chemical Industry (Tokyo, Japan). Phosphate buffered saline (PBS) was purchased from Takara Bio (Shiga, Japan). HPLC-grade acetonitrile was used. Water was purified using a Milli-Q system (Millipore, Bedford, MA, USA). All other chemicals were of analytical grade.

LE-overproducing Streptomyces globisporus 1912 strain was obtained in the laboratory of B. Matselyukh (D.K. Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kyiv). LE (99.5% purity, according to HPLC data) was prepared in the laboratory of J. Rohr (University of Kentucky, USA) and dissolved in absolute ethanol to obtain a 4 mg/ml stock solution. LA was isolated from S. cyanogenus S-136 following a previously published procedure, and L was prepared by hydrolysis using formic acid^{39 ,40} .
Menadione (MEN, Sigma Aldrich) was diluted in DMSO to obtain a 10 mM stock and stored at −20 °C. The thiol containing substances glutathione (L-GSH, ≥ 98%, Sigma Aldrich) and cysteine (L-Cys, ≥97%, Sigma Aldrich) and, in addition, the chemical GSH precursor N-acetylcysteine (NAC, ≥ 99%, Sigma Aldrich) were prior to each experiment freshly diluted in the indicated buffer or growth medium at indicated concentrations. GSH-synthesis inhibitor BSO (≥ 97%, Sigma Aldrich) was freshly diluted in ddH₂O prior to each experiment. All the other chemicals and solvents were purchased from Sigma-Aldrich and used without further purification.

L-GSH was purchased from Sigma-Aldrich (St. Louis, MO, USA), and D-GSH was obtained from KOMA Biotech (Seoul, Korea). The chirality of the GSHs was measured by CD spectroscopy (Chirascan-plus, Applied Photophysics, Leatherhead, UK). For the in vivo experiment, L- or D-GSH was dissolved to a concentration of 10 mM using 0.9% sterile saline in each case.