Mass spectra were recorded using direct inlet and electron impact ionization from two synthetic peptides, N-acetyl-aspartyl-4-aminobutyric acid and γ-glutamyl-taurine and a natural peptide, N-acetylaspartyl-glycyl-alanyl-aspartyl-serine, isolated from calf brain synaptosomes. The peptides were studied either underivatized or first acetylated with acetic acid anhydride and then permethylated with methyl iodide. The synthetic peptides were used to check the completeness of the derivatization reactions.
Abstract Leukocyte glutamate dehydrogenase (GDH) activity was measured in 11 healthy control subjects, 16 neurological controls, 12 patients with dominant late onset ataxia, 15 with sporadic late onset ataxia and 8 with alcoholic cerebellar ataxia. Serum hexosaminidase activity was also determined in ataxic patients. Concentrations of free amino acids were determined in the lumbal CSF of 16 neurological controls, 8 patients with late onset ataxia and 5 with alcoholic ataxia. Mean total GDH activity was reduced significantly in dominant (p < 0.05) and sporadic (p < 0.01) cerebellar ataxia, while the heat-labile form was decreased significantly (p < 0.01) only in sporadic ataxia. All GDH activities were within normal range in patients with alcoholic ataxia. The serum hexosaminidase activities were also within reference range in all patient groups. The CSF concentrations of alanine, glycine, methionine and valine were significantly elevated and those of GABA and glutamate were normal in patients with late onset ataxia as compared to neurological controls. The most significant (p < 0.01) increase was found for methionine. The amino acid levels of patients with alcoholic ataxia did not differ from those of the controls. The results suggest that GDH activity is only partially decreased in some ataxic patients and that altered amino acid metabolism may be reflected in the CSF.
Abstract The structure of a number of low‐molecular‐weight acidic peptides containing taurine prepared from calf brain synaptosomes and their subcellular vesicles was studied using electron impact mass spectrometry. At least seven sequences could be identified: N ‐acetylas‐partyl‐glutamyl‐taurine, N ‐acetylaspartyl‐taurine, N ‐ace‐tylglutamyl‐taurine, glutamyl‐taurine, aspartyl‐taurine, seryl‐glutamyl‐seryl‐taurine, and seryl‐taurine.
The effect of human transfer factor (TF) or its components L-serine and/or glycine in tuberculin (PPD), or leucoagglutinin (LA) induced leucocyte migration inhibitory factor (LIF) secretion was studied. Augmentation of LIF secretion was seen with low concentration ( = 0.078 g/l) of TF when lymphocytes were cultured in minimum essential medium for suspension cultures (MEM-S), a culture medium lacking L-serine and glycine. High concentrations (0.3125-5.0 g/l dry weight) of TF were inhibitory in MEM-S. In RPMI 1640, a culture medium containing L-serine and glycine, TF was either inhibitory or had no effect. The combination of L-serine and glycine, at concentrations equivalent or lower than the optimum of TF, had an augmenting effect on LIF secretion identical to that of TF, but no inhibition at higher concentrations was seen. The results indicate that human TF contains components which have suppressive or augmenting effects on LIF secretion in vitro. The augmenting effect may be mainly due to L-serine and glycine and thus not related to TF's activity in vivo.
