13C-NMR study of taurine and chlorotaurine in human cells.
13C-NMR with 13C-enriched taurine [( 13C]taurine) has been utilized to study the formation and reactions of N-chlorotaurine in solution and in human cells. Taurine reacts instantaneously with HOCl at pH 7.0 to form N-chlorotaurine, which is stable in solution by itself. In the presence of alpha-amino acids, a chlorine transfer reaction taken place to produce N-chloroamino acids, which quickly convert to the corresponding aldehydes. [13C]Taurine was incubated with human neutrophils and with cultured human lymphoblastoid cells and 13C-NMR spectra of the whole cell mixtures were acquired in order to examine the formation of N-chlorotaurine from reaction between taurine and the endogenous HOCl produced by myeloperoxidase-catalyzed reactions (Zgliczynski, J.M., et al. (1968) Eur. J. Biochem. 4, 540; Weiss, S.J., et al. (1982) J. Clin. Invest. 70, 598). The presence of N-chlorotaurine in the cells was not detected on the 13C-NMR spectra. On the other hand, N-chloro[13C]taurine incubated with the cells was found to be converted to taurine, which must have been produced by a chlorine transfer reaction of the N-chlorotaurine to other cellular components such as amino acids, peptides or proteins. A 13C-NMR study of taurine uptake in human lymphoblastoid cells indicated that taurine is incorporated into a freely mobile intracellular pool. These results suggest that the presence of abundant taurine in a freely mobile intracellular pool may serve as a buffer in preventing oxidative damage to the cells from attacks by HOCl or other oxidants.
Lin
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New York State Institute for Basic Research in Developmental Disabilities, Staten Island 10314.
Wright
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Zagorski
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Nakanishi
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D001692:Biological Transport; D002478:Cells, Cultured; D006801:Humans; D066298:In Vitro Techniques; D008214:Lymphocytes / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D013654:Taurine / Q000031:analogs & derivatives* / Q000378:metabolism*
D013654:Taurine; C043410:N-chlorotaurine