Non-enzymatic hydrogen sulfide production from cysteine in blood is catalyzed by iron and vitamin B₆.

ABSTRACT: Hydrogen sulfide (H₂S) plays important roles in metabolism and health. Its enzymatic generation from sulfur-containing amino acids (SAAs) is well characterized. However, the existence of non-enzymatic H₂S production from SAAs, the chemical mechanism, and its biological implications remain unclear. Here we present non-enzymatic H₂S production in vitro and in blood via a reaction specific for the SAA cysteine serving as substrate and requires coordinated catalysis by Vitamin B₆, pyridoxal(phosphate), and iron under physiological conditions. An initial cysteine-aldimine is formed by nucleophilic attack of the cysteine amino group to the pyridoxal(phosphate) aldehyde group. Free or heme-bound iron drives the formation of a cysteine-quinonoid, thiol g

SUBMITTER: Yang J 

PROVIDER: S-EPMC6529520 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature