ABSTRACT
Synthesis of a new family of quinolylhydrazone derivatives and evaluation of their activity against a chloroquine-resistant strain of Plasmodium falciparum are described. The best compound displayed an activity 6-fold higher than chloroquine. None of the active compounds were found to inhibit beta-hematin formation in vitro in the same range as chloroquine and five among them displayed lower calculated vacuolar accumulation ratios, suggesting the implication of a different mechanism of action.
Subject(s)
Antimalarials/chemical synthesis , Glyoxylates/chemical synthesis , Hydrazones/chemical synthesis , Animals , Antimalarials/pharmacology , Glyoxylates/pharmacology , Hydrazones/pharmacology , Plasmodium falciparum/drug effects , Plasmodium falciparum/growth & developmentABSTRACT
A novel linker, based on the anchoring of (+)-dimethyl 2,3-O-isopropylidene-D-tartrate to PEGA or PEG-PS solid supports, was developed for the solid-phase synthesis of C-terminal peptide alpha-oxo aldehydes. Peptide elongation was performed using the 9-fluorenylmethoxycarbonyl/t-Bu chemistry. The peptide and the 1,2-diol were deprotected on the solid phase. Then, a periodic oxidation of the fully deprotected peptidyl-resin led to the simultaneous cleavage of the product from the solid support and to the generation of the alpha-oxo aldehyde moiety. The methodology allowed the distance between the alpha-oxo aldehyde and the peptide to be easily modulated. The C-terminal peptide alpha-oxo aldehydes synthesized in this study were found to be useful partners in hydrazone, thiazolidine, and oxime chemical ligations.
Subject(s)
Aldehydes/chemical synthesis , Peptides/chemistry , Tartrates/chemistry , Chromatography, High Pressure Liquid , Oxidation-ReductionABSTRACT
A homologue of the human site-specific prolyl cis/trans isomerase PIN1 was identified in Arabidopsis thaliana. The PIN1At gene encodes a protein of 119 amino acids that is 53% identical with the catalytic domain of the human PIN1 parvulin. Steady-state PIN1At mRNA is found in all plant tissues tested. We show by two-dimensional NMR spectroscopy that the PIN1At is a prolyl cis/trans isomerase with specificity for phosphoserine-proline bonds. PIN1At is the first example of an eukaryotic parvulin without N- or C-terminal extensions. The N-terminal WW domain of 40 amino acids, typical of all the phosphorylation-dependent eukaryotic parvulins, is absent. However, triple-resonance NMR experiments showed that PIN1At contained a hydrophobic helix similar to the alpha1 helix observed in PIN1 that could mediate the protein-protein interactions.
Subject(s)
Arabidopsis/genetics , Peptidylprolyl Isomerase/genetics , Amino Acid Sequence , Arabidopsis/enzymology , Arabidopsis Proteins , Cloning, Molecular , Escherichia coli , Escherichia coli Proteins , Genes, Plant , Humans , Kinetics , Molecular Sequence Data , NIMA-Interacting Peptidylprolyl Isomerase , Nuclear Magnetic Resonance, Biomolecular , Peptidylprolyl Isomerase/chemistry , Peptidylprolyl Isomerase/metabolism , Phosphorylation , Plant Structures/enzymology , Protein Conformation , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino AcidABSTRACT
The Chemical Shift Index (CSI) method proposed by Wishart et al. [Biochemistry (1992) 31, 1647-1651] to evaluate the secondary structure of peptides in aqueous solution uses as its reference the chemical shift values of each of the 20 natural amino acids (X) in a typical nonstructured sequence GGXAGG (17-20). In order to apply the CSI method to protected resin-bound peptides, we established a new database of chemical shift values for the same GGXAGG sequences in their protected form and anchored to a polystyrene resin swollen in DMF-d7. The predictive value of this new reference set in the CSI protocol was tested on different resin-bound peptides that were previously characterized by a full NOE analysis.
