SYNTHESIS AND CHARACTERIZATION OF THIOBUTYLTRIPHENYLPHOSPHONIUM BROMIDE, A NOVEL THIOL REAGENT TARGETED TO THE MITOCHONDRIAL MATRIX

Mitochondria are continually exposed to oxidative stress due to supero xide formation by the respiratory chain which increases in pathologica l situations such as ischemia reperfusion and neurodegeneration. Durin g oxidative stress there are a number of changes in mitochondrial low- molecular-weight and protein thiols. In particular, the mitochondrial glutathione pool becomes oxidized and forms mixed disulfides with prot ein thiols. To investigate changes in the redox state and conjugation of mitochondrial glutathione, and other mitochondrial thiols, we desig ned and characterized a thiol probe specifically targeted to the mitoc hondrial matrix. This molecule, thiobutyltriphenyl-phosphonium bromide , contains a thiol group linked to a lipophilic triphenylphosphonium c ation which causes it to accumulate in the negatively charged mitochon drial matrix. Using [C-14] thiobutyltriphenylphosphonium bromide we co nfirmed that it was selectively accumulated by isolated mitochondria. In the mitochondrial matrix the thiol group equilibrated with endogeno us thiols and during oxidative stress became disulfide-bonded to prote in and nonprotein thiols. Therefore, this novel thiol probe can be use d to label protein thiol groups and to investigate changes in conjugat ion and redox state of mitochondrial thiols during oxdative stress. (C ) 1995 Academic Press, Inc.