TAILIEUCHUNG - Báo cáo khoa học: MR solution structure of the precursor for carnobacteriocin B2, an antimicrobial peptide fromCarnobacterium piscicola Implications of the a-helical leader section for export and inhibition of type IIa bacteriocin activity

Type IIa bacteriocins, which are isolated from lactic acid bacteria that are useful for food preservation, are potent antimicrobial peptides with considerable potential as therapeutic agents for gastrointestinal infections in mam-mals. They are ribosomally synthesized as precursors with an N-terminal leader, typically 18–24 amino acid residues in length, which is cleaved during export from the produ-cing cell. We have chemically synthesized the full precursor of carnobacteriocin B2, precarnobacteriocin (preCbnB2), which has a C-terminal amide rather than a carboxyl, and also produced preCbnB2(1–64), . | Eur. J. Biochem. 271 1748-1756 2004 FEBS 2004 doi NMR solution structure of the precursor for carnobacteriocin B2 an antimicrobial peptide from Carnobacterium piscicola Implications of the a-helical leader section for export and inhibition of type IIa bacteriocin activity Tara Snrules1 Karen E Kawulka1 Alan C Gibbs2. David S. Wishart2 and John C Vederas1 4 B 4 B F B B w B BBB B B B . B W B V V w B B w BB B B B BB . BV B w w BV BB w B BB B F . w B B B B B BB B B BB IV Bf B B B B BB . V BB BB BB B BB BV 1 Department of Chemistry and 2Faculty of Pharmacy University of Alberta Edmonton AB Canada Type IIa bacteriocins which are isolated from lactic acid bacteria that are useful for food preservation are potent antimicrobial peptides with considerable potential as therapeutic agents for gastrointestinal infections in mammals. They are ribosomally synthesized as precursors with an N-terminal leader typically 18-24 amino acid residues in length which is cleaved during export from the producing cell. We have chemically synthesized the full precursor of carnobacteriocin B2 precarnobacteriocin preCbnB2 which has a C-terminal amide rather than a carboxyl and also produced preCbnB2 1-64 which is missing two amino acid residues at the C-terminus Arg65 and Pro66 via expression in Escherichia coli as a maltose-binding protein fusion that is then cut with Factor Xa. PreC-bnB2 1-64 is readily labeled with 15N and 13C for NMR studies using the latter approach. Multidimensional NMR analysis of preCbnB2 1-64 shows that like the parent bacteriocin it exists as a random coil in water but assumes a defined conformation in water trifluoroethanol mixtures. In 70 30 trifluoroethanol water the 3D structure of the preCbnB2 section corresponding to the mature bacteriocin is essentially the same as reported previously by us for carnobacteriocin B2 CbnB2 . This structure maintains the highly conserved a-helix corresponding to residues 20-38 of CbnB2 that is .

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