Biosynthesis of taurine peptides in brain cytoplasmic fraction in vitro.
Brain homogenates and their cell-free soluble fraction incorporated labelled [14C]taurine, [14C]glutamic acid, [14C]aspartic acid and [14C]serine into a number of low-molecular weight peptides, among which glutamyl-, aspartyl- and seryl-taurines and their N-acetylated derivatives were identified. A partially purified cytoplasmic fraction catalyzed the formation of glutamyl-taurine. Excesses of aspartic acid and serine inhibited this reaction. Biosynthetic products were analyzed on thin-layer chromatography plates by an autoradiographic X-film technique and identified with the aid of synthetic peptides or endogenous synaptosomal peptides, whose structure was determined with mass spectrometry. gamma-Glutamyl-taurine was also formed through a group translocation mechanism from glutathione and taurine by the enzymes of the gamma-glutamyl cycle. The catalytic activity of the membraneous enzyme was identical with that of the commercial gamma-glutamyltransferase.
Lähdesmäki
P
P
Department of Biochemistry, University of Oulu, Finland.
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D002417:Cattle; D003593:Cytoplasm / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D010452:Peptide Biosynthesis; D013654:Taurine / Q000096:biosynthesis*
D000596:Amino Acids; D013654:Taurine