PubMed · 7024759
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B Willms. 1981-06-05. [Self-testing by the diabetic].. https://pubmed.ncbi.nlm.nih.gov/7024759/
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[reaction: see text] L-Proline-based small peptides have been developed as efficient catalysts for the asymmetric direct aldol reactions of hydroxyacetone with aldehydes. Chiral 1,4-diols 7, which are disfavored products in similar aldol reactions catalyzed by either aldolases or L-proline, were obtained in high yields and enantioselectivities of up to 96% ee with peptides 3 and 4 in aqueous media.
Intermolecular (1)H[(19)F] and (1)H[(1)H] nuclear Overhauser effects have been used to explore interaction of solvent components with melittin dissolved in 50% hexafluoroacetone trihydrate (HFA)/water. Standard nuclear Overhauser effect experiments and an analysis of C(alpha)H proton chemical shifts confirm that the conformation of the peptide in this solvent is alpha-helical from residues Ala4 to Thr11 and from Leu13 to Arg24. The two helical regions are not collinear; the interhelix angle (144 +/- 20 degrees ) found in this work is near that observed in the solid state and previous NMR studies. Intermolecular NOEs arising from interactions between spins of the solvent and the solute indicate that both fluoroalcohol and water molecules are strongly enough bound to the peptide that solvent-solute complexes persist for > or =2 ns. Preferential interactions of HFA with many hydrophobic side chains of the peptide are apparent while water molecules appear to be localized near hydrophilic side chains. These results indicate that interactions of both HFA and water are qualitatively different from those present when the peptide is dissolved in 35% hexafluoro-2-propanol/water, a chemically similar helix-supporting solvent system.
The popliteal lymph node (PLN) assay was proposed to detect the potential of immunotoxicants for inducing systemic autoimmune-like reactions, but also xenobiotics that are sensitizing or exert immunostimulatory properties. Results on over 100 chemicals, mostly pharmaceuticals, are available with the PLN assay and show many correlations between rodent data and the clinical experience. A major issue is that the mechanisms involved have not been fully elucidated. In order to provide mechanistic clues to improve the predictability of the PLN assay, the effects of streptozotocin (STZ) were compared to those of ethanol and acetone in normal C57Bl/6 mice as well as mice depleted in CD4+ or CD8+ T-cells by treatment with specific monoclonal antibodies. STZ, ethanol and acetone gave similar positive responses in normal mice. Neither CD4+ nor CD8+ T-cell depletion influenced the PLN responses to ethanol or acetone, whereas CD8+ in contrast to CD4+ T-cell depletion abolished the response to STZ. There was an increase in the production of IL-6 and IFN-gamma mRNAs measured by RT-PCR in STZ-, but not in ethanol- or acetone-treated normal mice. The production of TNFalpha, IL-1alpha, IL-1beta, IL-2R and IL-12 mRNAs was increased whatever the treatment, but increases were 2- to 3-fold greater after STZ than ethanol or acetone. These results suggest that PLN responses to primary irritants such as ethanol and acetone essentially reflect non-specific inflammation, whereas PLN responses to an autoimmunogenic compound such as STZ involve CD8+ T lymphocytes and the production of IFN-gamma and IL-6. These findings may prove useful to improve the predictability of the PLN assay.