The biosynthesis reaction of hypotaurine to taurine.

Abstract

Taurine (2-aminoethanesulfonic acid) is one of the most abundant amino acid-derived molecules in humans and most eukaryotes. Despite its many roles and functional properties, the biochemical mechanisms and the reaction of hypotaurine to taurine are still unknown. This study focuses on the biosynthesis reaction of hypotaurine to taurine in vivo and in vitro by using bioinformatics tools, enzymatic assays, and analytical techniques. Transcriptional co-expression analysis of 26 tissue and organ samples revealed Flavin- Monooxygenases (FMO) that seemed to be suitable candidates to catalyze the reaction of hypotaurine to taurine. However, enzymatic assay showed no chemical reaction on HPLC analysis after adding cofactors NAD+ and NADPH to HuH 7 hepatoma cells and 11 day-old embryonic chicken livers. Enzymatic assays failed to confirm an enzyme for the reaction of hypotaurine to taurine. Analytical assays were used to determine the spontaneous reaction of hypotaurine to taurine with Reactive Oxygen Species (ROS). HPLC, ESI-MS, NMR, FTIR and Raman assays were applied to investigate the reaction of hypotaurine and taurine with ROS such as superoxide, hydrogen peroxide, and singlet oxygen. HPLC and ESI-MS tests confirmed that hypotaurine did not react with singlet oxygen. However, various tests confirmed that hypotaurine reacted with hydrogen peroxide and superoxide. Analytical assay results revealed a novel molecule in the reaction of hypotaurine or taurine with superoxide. FTIR, NMR and Raman spectroscopy confirmed the characteristics of the novel molecule, peroxytaurine. Chemical methods to detect the peroxide in peroxytaurine was attempted with acridine, pyridine, and iron.