Design and Development of 2-Mercapto Malonodiamides as Substrates for 3-Mercaptopyruvate Sulfurtransferase (3-MST)

Abstract

Persulfides (RS-SH) are highly reactive and unstable species belonging to the category of reactive sulfur species (RSS), which are known to reduce oxidative stress. Low molecular weight persulfides like glutathione persulfide (GS-SH) and cysteine persulfide (CysS-SH) are significantly more effective at sequestering oxidants than thiols, and H2S and there is evidence that CysS-SH are better reductants. The enzymes cystathionine β synthase (CBS), cystathionine γ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (3 MST), and cysteinyl t-RNA synthetase (CARS) are involved in the manufacture of persulfide. Our lab has designed 2-mercapto malonatediester as a small molecule hydropersulfide generator. This molecule can transfer the sulfhydryl group to any thiol, including sulfurtransferase enzymes like 3-MST. We found that introduction of an amine (malonodiamide) instead of an ester inhibits the spontaneous sulfur transfer capability in these derivatives. Instead, malonodiamides were found to be excellent substrates for 3 MST. Here we have designed a series of these malonodiamide derivatives and tested their ability to produce H2S in the presence of 3-MST by in-vitro assays. Together, we have carried out a systematic structure-activity relationship study of this class of sulfur donors.