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Amyloid deposits within the cerebral tissue constitute a characteristic lesion associated with Alzheimer disease. They mainly consist of the amyloid peptide Abeta and display an abnormal content in Zn(2+) ions, together with many truncated, isomerized, and racemized forms of Abeta. The region 1-16 of Abeta can be considered the minimal zinc-binding domain(More)
Microcin E492 (MccE492, 7886 Da), the 84-amino acid antimicrobial peptide from Klebsiella pneumoniae, was purified in a post-translationally modified form, MccE492m (8717 Da), from culture supernatants of either the recombinant Escherichia coli VCS257 strain harboring the pJAM229 plasmid or the K. pneumoniae RYC492 strain. Chymotrypsin digestion of MccE492m(More)
Microcin J25 is a potent antibacterial peptide produced by Escherichia coli AY25. It displays a lasso structure, which consists of a knot involving an N-terminal macrolactam ring through which the C-terminal tail is threaded and sterically trapped. In this study, we rationally designed and performed site-specific mutations in order to pinpoint the sequence(More)
Microcin J25 (MccJ25) is the single representative of the immunity group J of the microcin group of peptide antibiotics produced by Enterobacteriaceae. It induces bacterial filamentation in susceptible cells in a non-SOS-dependent pathway [R. A. Salomon and R. Farias (1992) J. Bacteriol. 174, 7428-7435]. MccJ25 was purified to homogeneity from the growth(More)
The three-dimensional solution structure of microcin J25, the single cyclic representative of the microcin antimicrobial peptide class produced by enteric bacteria, was determined using two-dimensional 1H NMR spectroscopy and molecular modeling. This hydrophobic 21-residue peptide exhibits potent activity directed to Gram-negative bacteria. Its primary(More)
Microcin J25 (MccJ25) is a cyclic antibacterial peptide secreted by a fecal isolate of Escherichia coli. It exerts highly potent activity on Salmonella and Escherichia species. The microcin is recognized at the outer membrane of sensitive strains by the FhuA multifunctional protein, which belongs to the iron/siderophore receptor family, and inhibits(More)
Microcin J25 (MccJ25) is the single macrocyclic antimicrobial peptide belonging to the ribosomally synthesized class of microcins that are secreted by Enterobacteriaceae. It showed potent antibacterial activity against several Salmonella and Escherichia strains and exhibited a compact three-dimensional structure [Blond et al. (2001) Eur. J. Biochem., 268,(More)
The structure of a two-chain peptide formed by the treatment of the potent antimicrobial peptide microcin J25 (MccJ25) with thermolysin has been characterized by NMR spectroscopy and mass spectrometry. The native peptide is 21 amino acids in size and has the remarkable structural feature of a ring formed by linkage of the side chain of Glu8 to the(More)
Four new ether diglycosides (1-4), named matayosides A-D, were isolated from the root bark of Matayba guianensis, a plant exhibiting in vitro antiplasmodial activity. They were identified as hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-6-O-palmitoyl-beta-D-glucopyranoside,(More)
A phytochemical investigation of the constituents of the roots of Vismia laurentii has resulted in the isolation of two xanthone derivatives named laurentixanthone A (1) (6-hydroxy-3,3-dimethyl-11-(3-methylbut-2-enyl)pyrano[2,3-c]xanthen-7(3H)-one) and laurentixanthone B (2) (1-hydroxy-5,6,7,8-tetramethoxyxanthone), along with 11 known compounds:(More)