Production of hypotaurine from L-cysteinesulfinate by rat liver mitochondria.
Hypotaurine is the precursor of taurine production from L-cysteinesulfinate. It is recognized that hypotaurine production in the liver occurs in cytosol. In the present study, hypotaurine production from L-cysteinesulfinate in rat liver mitochondria was investigated. The mitochondrial preparation prepared according to the method of Hogeboom and washed repeatedly with 0.25 M sucrose solution was incubated with L-cysteinesulfinate. Products were derivatized with dabsyl chloride and dabsylated amino acids were analyzed by RP-HPLC. Presence of a peak corresponding to dabsyl-hypotaurine was confirmed. The peak of dabsyl-hypotaurine was converted quantitatively to dabsyl-taurine by the treatment with H(2)O(2). Optimum pH of the reaction was shown to be broad between 6.0 and 7.8 and Km for L-cysteinesulfinate was 0.11 mM. Results indicate the presence of L-cysteinesulfinate decarboxylase activity in liver mitochondria. Mitochondrial cysteine metabolism was summarized and possible antioxidant roles of cysteine metabolites including hypotaurine in mitochondria are discussed.
Ubuka
T
T
Department of Clinical Nutrition, Kawasaki University of Medical Welfare, Kurashiki, Okayama, Japan. ubukatos@mw.kawasaki-m.ac.jp
Okada
A
A
Nakamura
H
H
D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000378:metabolism*; D003545:Cysteine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D013654:Taurine / Q000031:analogs & derivatives* / Q000096:biosynthesis
D000975:Antioxidants; D013654:Taurine; C003949:hypotaurine; D002262:Carboxy-Lyases; C019972:sulfoalanine decarboxylase; D003545:Cysteine; C013461:cysteine sulfinic acid