D- and N-Methyl Amino Acids for Modulating the Therapeutic Properties of Antimicrobial Peptides and Lipopeptides.

Here we designed and synthesized analogs of two antimicrobial peptides, namely C10:0-A2, a lipopeptide, and TA4, a cationic α-helical amphipathic peptide, and used non-proteinogenic amino acids to improve their therapeutic properties. The physicochemical properties of these analogs were analyzed, including their retention time, hydrophobicity, and critical micelle concentration, as well as their antimicrobial activity against gram-positive and gram-negative bacteria and yeast. Our results showed that substitution with D- and N-methyl amino acids could be a useful strategy to modulate the therapeutic properties of antimicrobial peptides and lipopeptides, including enhancing stability against enzymatic degradation.

A Comparative Study of the Antimicrobial and Structural Properties of Short Peptides and Lipopeptides Containing a Repetitive Motif KLFK.

Background: In the last years, Antimicrobial Peptides (AMPs) and lipopeptides have received attention as promising candidates to treat infections caused by resistant microorganisms.

Objective: The main objective of this study was to investigate the effect of repetitive KLFK motifs and the attachment of aliphatic acids to the N-terminus of (KLFK)n peptides on therapeutic properties.

Methods: Minimal inhibitory concentration against Gram (+) and (-) bacteria and yeast of synthetic compounds were determined by broth microtiter dilution method, and the toxicity was evaluated by hemolysis assay.

Amphibian Skin Secretions as a Novel Source for the Isolation of Antibacterial Peptides.

Amphibians´ skin produces a diverse array of antimicrobial peptides that play a crucial role as the first line of defense against microbial invasion. Despite the immense richness of wild amphibians in Argentina, current knowledge about the presence of peptides with antimicrobial properties is limited to a only few species. Here we used LC-MS-MS to identify antimicrobial peptides with masses ranging from 1000 to 4000 Da from samples of skin secretions of (Anura: Leptodactylidae).

Natural Multi-Target Inhibitors of Cholinesterases and Monoamine Oxidase Enzymes with Antioxidant Potential from Skin Extracts of Hypsiboas cordobae and Pseudis minuta (Anura: Hylidae).

Alzheimer's disease (AD) is the most common cause of dementia, characterized by loss of selective neuronal and normal brain functions. Every year, ten million new cases are diagnosed worldwide. AD is a complex disease associated with all kind of different pathways, making their simultaneous modulation necessary.

Molecular design and synthesis of novel peptides from amphibians skin acting as inhibitors of cholinesterase enzymes.

Cholinesterases are a family of enzymes that catalyze the hydrolysis of neurotransmitter acetylcholine. There are two types of cholinesterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), which differ in their distribution in the body. Currently, cholinesterase inhibitors (ChEI) represent the treatment of choice for Alzheimer's disease (AD).

Biological and structural effects of the conjugation of an antimicrobial decapeptide with saturated, unsaturated, methoxylated and branched fatty acids.

The increasing bacterial resistance against conventional antibiotics has led to the search for new antimicrobial drugs with different modes of action. Cationic antimicrobial peptides (AMPs) and lipopeptides are promising candidates to treat infections because they act on bacterial membranes causing rapid destruction of sensitive bacteria. In this study, a decapeptide named A2 (IKQVKKLFKK) was conjugated at the N-terminus with saturated, unsaturated, methoxylated and methyl -branched fatty acids of different chain lengths (C8 - C20), the antimicrobial and structural properties of the lipopeptides being then investigated.

Combined analysis of cross-reacting antibodies anti-β1AR and anti-B13 in advanced stages of Chagas heart disease.

Objective: Autoantibodies cross-reacting with the β1 adrenergic receptor (anti-β1AR and anti-p2β) and cardiac myosin antigens (anti-B13) have been related to the pathogenesis of chronic Chagas heart disease (CCHD). Studies exploring their levels in different stages are scarce. We aimed to evaluate the relationship of these autoantibodies with the clinical profile of chronic patients, especially regarding their classificatory accuracy in severe presentation with heart failure.

Antimicrobial peptides from skin secretions of Hypsiboas pulchellus (Anura: Hylidae).

The skin of many amphibians produces a large repertoire of antimicrobial peptides that are crucial in the first line of defense against microbial invasion. Despite the immense richness of wild amphibians in Argentina, knowledge about peptides with antimicrobial properties is limited to a few species. Here we used LC-MS-MS to analyze samples of Hypsiboas pulchellus skin with the aim to identify antimicrobial peptides in the mass range of 1000 to 2000 Da.

Contribution of the Tyr-1 in Plantaricin149a to disrupt phospholipid model membranes.

Plantaricin149a (Pln149a) is a cationic antimicrobial peptide, which was suggested to cause membrane destabilization via the carpet mechanism. The mode of action proposed to this antimicrobial peptide describes the induction of an amphipathic α-helix from Ala7 to Lys20, while the N-terminus residues remain in a coil conformation after binding. To better investigate this assumption, the purpose of this study was to determine the contributions of the Tyr1 in Pln149a in the binding to model membranes to promote its destabilization.

Interaction of acylated and substituted antimicrobial peptide analogs with phospholipid-polydiacetylene vesicles. Correlation with their biological properties.

A series of peptide analogs based on region 6-22 of Plantaricin 149 sequence were synthesized. The interaction between these analogs and phospholipid-polydiacetylene vesicles was investigated to evaluate the ability of the bioassay to detect differences in the interaction of the peptides with dipalmitoylphosphatidylglycerol and dipalmitoylphosphatidylcholine vesicles, associated with amino acid substitution and N-terminal conjugation of the sequences with short fatty acids (8 and 12 carbon atoms). Fatty acid conjugation of peptides with low antimicrobial activity resulted in lipopeptides with improved activity against strains of Staphylococcus aureus and Listeria monocytogenes.

Bactericidal and hemolytic activities of synthetic peptides derived from granulysin.

Granulysin is a human polypeptide produced by cytolytic cells active against a broad range of microbes. Three peptides covering the regions 25-50 (Gr-1 and Gr-2) and 39-62 (Gr-3) of granulysin were synthesized, and their in vitro activity against Mycobacterium tuberculosis was evaluated. The most active peptide was Gr-1C, containing a disulphide bridge, with Minimal Inhibitory Concentration value of 10.

Epitope mapping of pathogenic Leptospira LipL32.

Aims: To identify LipL32 epitopes and to evaluate their capability to recognize specific antibodies using ELISA.

Methods And Results: Epitope mapping by means of a library of overlapping peptide fragments prepared by simultaneous and parallel solid phase peptide synthesis on derivatized cellulose membranes (SPOT synthesis) was carried out. Eighty-seven overlapping decapentapeptides corresponding to the complete sequence of LipL32 were synthesized.

Disruption of Saccharomyces cerevisiae by Plantaricin 149 and investigation of its mechanism of action with biomembrane model systems.

The action of a synthetic antimicrobial peptide analog of Plantaricin 149 (Pln149a) against Saccharomyces cerevisiae and its interaction with biomembrane model systems were investigated. Pln149a was shown to inhibit S. cerevisiae growth by more than 80% in YPD medium, causing morphological changes in the yeast wall and remaining active and resistant to the yeast proteases even after 24 h of incubation.

Characterization and purification of a new bacteriocin with a broad inhibitory spectrum produced by Lactobacillus plantarum lp 31 strain isolated from dry-fermented sausage.

Aims: Characterization and purification of a new bacteriocin produced by Lactobacillus plantarum LP 31 strain, isolated from Argentinian dry-fermented sausage.

Methods And Results: Lactobacillus plantarum LP 31 strain produces an antimicrobial compound that inhibits the growth of food-borne pathogenic bacteria. It was inactivated by proteolytic enzymes, was stable to heat and catalase and exhibited maximum activity in the pH range from 5.

Systematic epitope analysis of the p26 EIAV core protein.

The major core protein of equine infectious anemia virus (EIAV), p26, is one of the primary immunogenic structural proteins during a persistent infection of horses and is highly conserved among antigenically variants of viral isolates. In order to investigate its immune profile in more detail for a better diagnostic, an epitope mapping was carried out by means of two libraries of overlapping peptide fragments prepared by simultaneous and parallel SPPS on derivatized cellulose membranes (SPOT synthesis). Polyclonal equine sera from infected horses were used for the biological assay.

[In-vitro activity of two hybrid synthetic peptides having antimicrobial activity against mycobacteria].

The increase in both Mycobacterium tuberculosis human clinical isolates resistant to the essential drugs and cases of disseminated micobacteriosis due to Mycobacterium avium Complex, underlines the need to investigate new antimicobacterial agents. The antimicrobial peptides are a new group of active antibiotics with a particular mechanism of action. Some of them, like cecropin and melittin, isolated from insects, have demonstrated good in vitro activity against Gram-positive and Gram-negative bacteria.

A synthetic analog of plantaricin 149 inhibiting food-borne pathogenic bacteria:evidence for alpha-helical conformation involved in bacteria-membrane interaction.

Plantaricin-149 is a bacteriocin produced by Lactobacillus plantarum NRIC 149 (a LAB isolated from pineapple), which consists of a peptidic chain made up of 22 amino acid residues [Kato et al. J. Ferment.

Antibodies and PMBC from EIAV infected carrier horses recognize gp45 and p26 synthetic peptides.

Equine infectious anemia virus (EIAV) is a lentivirus causing a persistent infection in horses characterized by recurrent febrile episodes and high levels of viremia associated with a novel antigenic strain of the virus. The virus contains two envelope glycoproteins, gp90 and gp45, and four internal proteins, p26, p15, p11 and p9. Considering that the most infected horses are able to restrict EIAV replication to very low levels and that gp45 and p26 contain highly conserved epitopes among lentiviruses, it would be necessary to identify those conserved epitopes stimulating cellular and humoral responses.

Antibody recognition of synthetic peptides mimicking immunodominant regions of HIV-1 p24 and p17 proteins.

The gag gene of HIV-1 encodes a single open reading frame of 55 kDa that contains three subdomains: the matrix domain (p17), the capsid domain (p24) and the nucleocapsid domain (p15). The p24 and p17 proteins have a predominant alpha-helical structure and perform important functions throughout the viral life-cycle. The determination of gag-specific antibodies is important because declining titers of these antibodies herald clinical deterioration.

Cooperative effects in phospholipid monolayers induced by a peptide from HIV-1 capsid protein.

The study of interactions between biological molecules and model membranes is essential for the understanding of a number of physiological mechanisms involved in viral infections and dissemination. In this paper, the analysis of the interaction between a peptide from the p24 protein of Human Immunodeficiency Virus type 1 (HIV-1) and a phospholipid monolayer has pointed to a cooperative response in which very small amounts of peptide p24-1 (e.g.

Conformation of a synthetic antigenic peptide from HIV-1 p24 protein induced by ionic micelles.

We studied the interaction of the peptide AAMQMLKETINEEAAEWDRVHPVHAGPIA from the HIV-1 p24 protein in the presence of SDS (anionic) and CTABr (cationic) micelles at pH 7.0 by circular dichroism, fluorescence, and electron spin resonance (ESR). The micelles induced secondary structure as well as a blue shift in the tryptophan fluorescence emission, indicating an interaction between the peptide and the micelles.

[Evaluation of synthetic peptides for the detection of antibodies against human immunodeficiency virus].

The serologic diagnosis of human immunodeficiency virus (HIV) infection is currently done by detecting the presence of antibodies against the different antigenic viral proteins through immunoassays and later confirmation by Western blot. Several types of antigens can be used in immunoassays, but recombinant proteins and synthetic peptides are the most frequently used. In this paper, peptides mimicking antigenic regions from p24 (region 196-224), gp41 (region 600-614) and gp120 (region 303-338, Loop V3) proteins of HIV-1 have been used as antigens in an enzyme-linked immunosorbent assay and their reactivity was screened against a panel of positive and negative sera.

Design and validation of an ELISA for equine infectious anemia (EIA) diagnosis using synthetic peptides.

Three peptides derived from the equine infectious anemia virus (EIAV) surface proteins were synthesized to design and validate an ELISA for EIA diagnosis. Peptides identified as gp90-I and gp90-II correspond to the N- and C-terminal part of the surface glycoprotein gp90. Peptide gp45-1 overlaps the immunodominant epitope CIERTHVFC of the transmembrane glycoprotein gp45, and includes a hydrophilic chain close to the N-terminal end of this nonapeptide loop.

[Utility of gas chromatography for the identification of mycobacterial species].

The human immunodeficiency virus (HIV) epidemic has altered the epidemiological profile of tuberculosis in both industrialized and developing countries. Serious diseases caused by mycobacteria other than Mycobacterium tuberculosis, mostly belonging to the M. avium-intracellulare complex (MAC), have become very common in association with severe immunosuppression.

Differential distribution of gonadotropin-releasing hormone variants in the brain of Hydrochaeris hydrochaeris (Mammalia, Rodentia).

1. In a previous paper we reported evidence for the presence of mGnRH- and sGnRH-like peptides in the preoptic-hypothalamic region of the capybara Hydrochaeris hydrochaeris (Montaner et al., 1998).