Search

Research has been conducted on the peptide toxin isolated from a spider venom. The primary sequence and three-dimensional structure of this toxin have been investigated via the use of the NMR spectroscopy and the results indicate that in solution the molecule contains conformations produced by the cis/trans isomerization of its proline residue.

The trypsin inhibitor BSTI from Bombina bombina frog consists of 60 residues with five disulfide bonds and a secondary structure of four beta-strands arranged in two antiparallel beta-sheets. BSTI is folded into a disc shape with no hydrophobic core and the active site located in a loop made of 21-34 residues.

The tertiary structure of retrocyclin-2 is determined in a membrane-mimicking environment and a well-defined [beta]-hairpin structure is present in the presence of SDS micelles. The ability to self-associate has contributed to the high-affinity binding of retrocyclins for glycoproteins by increasing the valency and increasing the ability of retrocyclins to cross-link cell surface glycoproteins.

The three-dimensional structure determined using (super 1)H NMR spectroscopy is presented and the potent insecticidal activity for one of these peptides, kalata B2 is demonstrated. Examination of the sequence reveals that they could be separated in to two subfamilies, one of which contains a larger number of positively charged residues and has a bracelet-like circularization of the backbone, and the other contains a backbone twist due to a cis-peptidyl-proline bond and might conceptually be regarded as a molecular Mobius strip.

Enterocin NKR-5-3B, one of the multiple bacteriodns produced by Enterococcus faecium NKR-5-3, is a 64-amino add novel drcular bacteriocin that displays broad-spectrum antimicrobial activity. Here we report the identification, characterization, and three-dimensional nuclear magnetic resonance solution structure determination of enterocin NKR-5-3B. Enterodn NKR-5-3B is characterized by four helical segments that enclose a compact hydrophobic core, which together with its circular backbone impart high stability and structural integrity. We also report the corresponding structural gene, enkB, that encodes an 87-amino add precursor peptide that undergoes a yet to be described enzymatic processing that involves adjacent cleavage and ligation of Leu24 and Trp87 to yield the mature (drcular) enterocin NKR-5-3B. [ABSTRACT FROM AUTHOR]

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 N-terminus that is threaded by the C-terminal tail of the peptide. Thermolysin cleaves the peptide at the Phe10-Vall 1 amide bond, but the threading of the C-terminus through the N-terminal ring is so tight that the resultant two chains remain associated both in the solution and in the gas phases. The three-dimensional structure of the thermolysin-cleaved peptide derived using NMR spectroscopy and simulated annealing calculations has a well-defined core that comprises the N-terminal ring and the threading C-terminal tail. In contrast to the well-defined core, the newly formed termini at residues PhelO and Vall 1 are disordered in solution. The C-terminal tail is associated to the ring both by hydrogen bonds stabilizing a short β-sheet and by hydrophobic interactions. Moreover, unthreading of the tail through the ring is prevented by the bulky side chains of Phe19 and Tyr20, which flank the octapeptide ring. This noncovalent two-peptide complex that has a remarkable stability in solution and in highly denaturing conditions and that survives in the gas phase is the first example of such a two-chain peptide lacking disulfide or interchain covalent bonds. [ABSTRACT FROM AUTHOR]