Biosynthesis of Taurine Peptides in Brain Cytoplasmic Fraction in Vitro

Abstract

Brain homogenates and their cell-free soluble fraction incorporated labelled [¹¹C]taurine, [¹¹C]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. γ-Glutamyl-taurine was also formed througn a group translocation mechanism from glutathione and taurine by the enzymes of the γ-glutamyl cycle. The catalytic activity of the membraneous enzyme was identical with that of the commercial γ-glutamyltransferase.

Key Words:

• taurine peptides
• glutamic acid
• aspartic acid

Additional information

Notes on contributors

P. Lähdesmäki

Joyce Laing works in the Department of Child and Family Psychiatry, Playfield House, Cupar, Fife, and is a Consultant Art Therapist to Psychiatric Hospitals and Prisons and Chairwoman of the Scottish Society of Art and Psychology.