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The effect of substituting two glycine residues, Gl[y.sup.8] and Gl[y.sup.13] with Ala or Pro on the peptide's structure and biological activities is examined to develop novel antibiotic peptides with selectivity for bacterial cells. It is demonstrated that the Gly-Pr[o.sup.8] is an excellent candidate lead compound for the development of novel antimicrobial agents.

High-throughput methods for the preparation of nonmevalonate terpene biosynthesis enzymes, which can be effectively used as antiinfective drugs, are described. Enzyme-assisted methods for the preparation of the required substrates in multigram amounts, with or without (13.Super)C labels in various positions that enable monitoring of enzyme reaction by (13.Super)C NMR, are presented.

The rotational-echo double-resonance solid-state NMR distance measurements are employed to the intermolecular packing and the membrane-bound dimer structure of a [beta]-hairpin antimicrobial peptide, Protegrin-1 (PG-1) in various lipid bilayers. The analysis shows that the peptide is parallely packed in the lipid bilayer and may be stabilized by strong amphipathic character and hence facilitates its insertion in the amphipathic lipid bilayer.

The role of amphipathicity using an analogue of tachyplesin 1(TP-1), CDT (KWFRVYRGIYRRR-N[H.sub.2]), in which all four cysteines were deleted were investigated. The properties help to explain that cysteine residues may not contribute to antimicrobial activity and that the loss of hemolytic activity is due to lack of hydrophobicity and amphipathicity.

The prevalence and antimicrobial resistance of Campylobacter isolates from both conventionally raised and organically raised broilers and turkeys are determined. The analysis has revealed the effect of conventional and organic poultry production practices on antimicrobial resistance of Campylobacter on poultry farms.

Antimicrobial peptides (AMPs) are old components of innate immunity found in all living pluricellular organisms. The study highlights the importance of a single alpha-amino acid epimerization as a tool used by nature to modulate the activity of AMPs and the findings suggest bombinins H as potential templates for the development of new drugs with a new mode of action against Leishmania.

An observation about SigB that contributes positively to Listeria monocytogenes tolerance of the bacteriocins nisin and lacticin 3147 and of the antibiotics ampicillin and penicillin G. is presented. The results showed that SigB might contribute to the survival of Listeria monocytogenes both in the food-processing environment and in vivo during infection which might represent an attractive target for the development of new control and treatment strategies for this important pathogen.

A three-dimensional computer model of bio-film dynamics was developed as a tool for investigating mechanisms of protection from antimicrobial agents in bio-films. The differences between the protective mechanisms predicted in these simulations could guide the design of experiments to discriminate antimicrobial tolerance mechanisms in biofilms.

Sum frequency generation (SFG) vibrational spectroscopy is employed to study the molecular interactions between a single substrate supported lipid bilayer and an amphiphilic antibiotic compound with a designed based on the common structural motif of natural antimicrobial peptides. The interfacial sensitivity of SFG allows real-time in situ monitoring of ordering changes in both leaflets of the bilayer and orientation of the compound simultaneously.

Byline: L. A. Smit (1), N. Haagsma (1), A. Ruiter (1) Keywords: Key wordsaSulphadimidine; Fermented sausage; Carbon-14-labelling; Rat; Bound residues Abstract: aSulphadimidine (SDM), a drug frequently administered to pigs, is partially converted into other compounds by processing meat to produce raw, fermented sausage. With the aid of 14.sup.C-labelled SDM, evidence was obtained that part of the radioactive matter was covalently bound to the matrix. Part of these bound residues could be released in vitro by 4M HCl at 21aadegC or by 0.024M HCl at 37aadegC. Female rats were also able to release bound SDM residues and to excrete these in their urine, in amounts approaching those obtained by treatment with 4M HCl. Both the parent compound and its main metabolite, N .sup.4-acetyl-SDM, were observed in the urine of rats. Author Affiliation: (1) Department of the Science of Food of Animal Origin, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80.175, 3508 TD Utrecht, The Netherlands, NL Article note: Received: 29 December 1997 / Revised version: 20 February 1998

Byline: Jan RA-zicka (1), KateAina Velclova (1), Rahula Janis (1), JiAi Krejci (1) Keywords: Monoacylglycerols; Antimicrobial activity; Bacteria; Fungi; Yeasts Abstract: This study was aimed at assessing the effects exhibited by two types of monoacylglycerols (monocaprin and monolaurin, prepared by reactions of glycidol with the corresponding fatty acids) against important species of bacteria, filamentous fungi and yeast-like organisms. Results of determined minimal inhibitory concentrations (MICs) showed that monocaprin at concentrations of 100--250 mg/l is able to stop completely the growth of all Gram-positive bacteria and yeasts tested, and at concentrations of 100--400 mg/l, the growth of most filamentous fungi. On the other hand, some Gram-negative bacteria and also the fungus Mucor racemosus proved to be resistant to monocaprin. The antimicrobial spectrum of monolaurin was clearly narrower, and almost exclusively involved Gram-positive bacterial species, with levels of MICs from 20 to 200 mg/l. Author Affiliation: (1) Faculty of Technology, Tomas Bata University in Zlin, T.G.M. 275, 762 72, Zlin, Czech Republic Article History: Received Date: 26/05/2003 Online Date: 14/08/2003

Several studies are conducted to explain the formation and properties of the bifunctional layer-by-layer (LbL) construct made by the combination of permanent microbicidal polyelectrolyte multilayered (PEM) base film with a hydrolytically degradable PEM top film. These films are shown to be extremely efficient and hence can be used as coatings for different implantable devices.

Novel analogues of melittin were designed by substituting the leucine residue(s) at the 'd' and 'a' positions of its previously identified leucine zipper motif to understand the lytic activities of melittin antimicrobial peptide against bacteria and mammalian cells. The data revealed that the substitution of hydrophobic leucine residue(s) by lesser hydrophobic alanine residue(s) in the leucine zipper sequence of melittin disturbed its pore-forming activity and mechanism only in hRBCs but not in the tested bacteria.

The structure of the par toxin Fst, the first atomic resolution structure of a component of an antisense regulated toxin-antitoxin system, is described. The studies have shown that Fst has displayed neither hemolytic nor antimicrobial activity when applied externally to a series of bacteria, fungal cells and erythrocytes and also its charge distribution, orientation in the membrane and structure has distinguished it from antimicrobial peptides.

[Super 31]P and [super 19]F solid-state NMR spectroscopy are applied to study the the lipid interaction, depth of insertion, orientation, and dynamics of an arylamide, PMX30016 and gain better insight into the mechanism of action of the antimicrobial arylamide foldamers. The results suggested that antimicrobial arylamides destabilize anionic lipid membranes primarily by altering the membrane electric potential profile, and the spinning molecular knife might additionally create transient defects in the lipid membrane.

Extensive 2D NMR and MS techniques were used for structural characterization of eight new antimicrobial natural products named chrysophaentins A-H belonging to a new structural class isolated from the marine chrysophyte alga Chrysophaeum taylori. Chrysophaentin A, identified as one of the most potent antibiotic, inhibited the growth of clinically relevant gram-positive bacteria including methicillin-resistant Staphylococcus aureus, multidrug-resistant S. aureus and vancomycin-resistant Enterococcus faecium.

[Super 19]F NMR solid-state analysis was performed to isolate native membranes from erythrocyte ghosts and bacterial protoplasts and prepare them as macroscopically oriented samples. The characteristic fingerprint splitting of the membrane-bound antimicrobial peptide PGLa detected by [super 19]F reporter group indicated that the peptide helix binds to the native membranes in a surface alignment, although with a higher affinity in the prokaryotic than the eukaryotic system.

The article presents a new approach, where in the measurements of diffusion times can be employed for studying the antimicrobial peptide (AMP)-membrane interactions. The methodology is shown to be extremely beneficial in studying the membrane structures at extremely low peptide ratios.

A paramagnetic copper-chelated lipid is used to enhance the spin-lattice relaxation and thereby speed up solid-state NMR measurements. The results have shown a 6.2-fold speed increase and a 2.7-fold improvement in signal-to-noise ratio for solid-state NMR experiments under magic-angle spinning and static conditions.

A study was conducted to gain insight into the toxic properties and the role of anionic lipid clustering of five antimicrobial peptides which consists of peptides that form cationic amphipathic helices on membranes. Gram-positive bacteria showed a predominance of anionic lipids in the cytoplasmic membrane while gram-negative bacteria, which exhibit clustering of anionic lipids away from zwitterionic ones, could contribute significantly to the mechanism of bacterial toxicity for some antimicrobial agents.

The article presents a new approach, which employs a modified nonwoven fabric as a thin film detection/response system for the pathogenic bacteria. The systems are shown to be widely used as responsive dressings with the release of antimicrobials.

Cloning, sequencing, and heterologous expression of the cyclothiazomycin biosynthetic gene cluster from Streptomyces hygroscopicus 10-22 is reported. The rigorous bioinformatics analysis based on heterologous expression of cyclothiazomycin led to an ideal biosynthetic model to better understand the biosynthesis of thiopeptides.

A study was conducted to examine the metabolic activity like oxygen consumption and acid formation and viability and the effect of antimicrobial chlorhexidine (CHX) treatment on the physiology of the dental biofilms during exposure to sucrose. The CHX exposure was observed to reduce the metabolic activity and microbial viability at the biofilm surface and drove metabolic activity deeper into the biofilm.

The role of the leader peptide of McjA is examined and is shown that only the eight C-terminal amino acids of this leader peptide are needed for maturation of the antimicrobial peptide microcin J25 (MccJ25). Alanine scanning mutagenesis studies have shown that the Thr-35 residue in the leader peptide is vital for correct processing of McjA into mature MccJ25, whereas the charged amino acids have not played a major role in the maturation of MccJ25.

The various effects of the linear cationic antimicrobial peptide structures on the inhibition of the planktonic growth and biofilm formation in Escherichia coli are discussed. The hexameric, as well as the octameric peptides are shown to be the best inhibitors of the discussed growth.

Two members, temporin A (TA) and temporin L (TL) from temporins which constitute a family of amphipathic [alpha]-helical antimicrobial peptides (AMPs) and contain some of the shortest cytotoxic peptides are examined to understand their spectra of antimicrobial activity and toxicity. NMR studies indicated that strongly hemolytic [Gln.sup.3]-TA exhibited stable helical conformation along the entire sequence, while weakly hemolytic but antimicrobial [Pro.sup.3]-TL showed conformational averaging at the N-terminus.

A new method is described for obtaining information about the conformational dynamics of membrane-proteins by using solid-state NMR experiments of oriented samples. The method is shown for the antimicrobial peptaibol alamethicin for which combined analysis of anisotropic interactions for the [Aib.sub.8] residue has given information about helix-tilt angle, wobbling and oscillatory rotation around the helix axis in the membrane bound state.