Insights into self-degradation of cysteine esters and amides under physiological conditions yield new cleavable chemistry.

An unprecedented H 2 S release from cysteine esters and amides (CysO/NHR) under physiological conditions was discovered and the plausible mechanism was proposed. Alkylation of the amino moiety of cysteine esters enables the H 2 S release to be tuned and further provides support to the mechanistic insights. This discovery not only provides new insights into several fundamental science issues including non-enzymatic H 2 S-produced pathways, but also inspires new tunable cleavable motifs for sustained release of arylthiols and even for prodrug design.