scholarly journals D-Amino Acid-Containing Lipopeptides Derived from the Lead Peptide BP100 with Activity against Plant Pathogens

2021 ◽  
Vol 22 (12) ◽  
pp. 6631
Author(s):  
Àngel Oliveras ◽  
Luís Moll ◽  
Gerard Riesco-Llach ◽  
Arnau Tolosa-Canudas ◽  
Sergio Gil-Caballero ◽  
...  
Keyword(s):  
Biological Activity ◽  
Amino Acid ◽  
Secondary Structure ◽  
Pathogenic Bacteria ◽  
Plant Pathogens ◽  
Biological Profile ◽  
High Antimicrobial Activity ◽  
Hydrophobic Chain ◽  
Bacteria And Fungi ◽  
Α Helix

From a previous collection of lipopeptides derived from BP100, we selected 18 sequences in order to improve their biological profile. In particular, analogues containing a D-amino acid at position 4 were designed, prepared, and tested against plant pathogenic bacteria and fungi. The biological activity of these sequences was compared with that of the corresponding parent lipopeptides with all L-amino acids. In addition, the influence of the length of the hydrophobic chain on the biological activity was evaluated. Interestingly, the incorporation of a D-amino acid into lipopeptides bearing a butanoyl or a hexanoyl chain led to less hemolytic sequences and, in general, that were as active or more active than the corresponding all L-lipopeptides. The best lipopeptides were BP475 and BP485, both incorporating a D-Phe at position 4 and a butanoyl group, with MIC values between 0.8 and 6.2 µM, low hemolysis (0 and 24% at 250 µM, respectively), and low phytotoxicity. Characterization by NMR of the secondary structure of BP475 revealed that the D-Phe at position 4 disrupts the α-helix and that residues 6 to 10 are able to fold in an α-helix. This secondary structure would be responsible for the high antimicrobial activity and low hemolysis of this lipopeptide.

scholarly journals Plant thionins: structure, biological functions and potential use in biotechnology

2018 ◽  
Vol 22 (6) ◽  
pp. 667-675 ◽  
Author(s):  
T. I. Odintsova ◽  
M. P. Slezina ◽  
E. A. Istomina
Keyword(s):  
Pathogenic Bacteria ◽  
Plant Pathogens ◽  
Biological Activities ◽  
Three Dimensional ◽  
Amino Acid Sequences ◽  
Lipid Transfer ◽  
Human Pathogens ◽  
Candida Spp ◽  
Wide Range ◽  
Bacteria And Fungi

Antimicrobial peptides (AMPs) are important components of defense system in both plants and animals. They represent an ancient mechanism of innate immunity providing rapid first line of defense against pathogens. Plant AMPs are classified into several families: thionins, defensins, nonspecific lipid-transfer proteins, hevein- and knottin-type peptides, hairpinins and macrocyclic peptides (cyclotides). The review focuses on the thionin family. Thionins comprise a plant-specific AMP family that consists of short (~5 kDA) cysteine-rich peptides containing 6 or 8 cysteine residues with antimicrobial and toxic properties. Based on similarity in amino acid sequences and the arrangement of disulphide bonds, five structural classes of thionins are discriminated. The three-dimensional structures of a number of thionins were determined. The amphipathic thionin molecule resembles the Greek letter Г, in which the long arm is formed by two antiparallel α-helices, while the short one, by two parallel β-strands. The residues responsible for the antimicrobial activity of thionins were identified. Thionins are synthesized as precursor proteins consisting of a signal peptide, the mature peptide region and the C-terminal prodomain. Thionins protect plants from pathogenic bacteria and fungi acting directly on the membranes of microorganisms at micromolar concentrations, although their precise mode of action remains unclear. In addition to plant pathogens, thionins inhibit growth of a number of human pathogens and opportunistic microorganisms, such as Candida spp., Saccharomyces cerevisiae, Fusarium solani, Staphylococcus aureus and Escherichia coli. Thionins are toxic to different types of cells including mammalian cancer cell lines. Transgenic plants expressing thionin genes display enhanced resistance to pathogens. A wide range of biological activities makes thionins promising candidates for practical application in agriculture and medicine.

Weitere Untersuchungen zur Aminosäuresequenz des Melittins

1969 ◽  
Vol 24 (1) ◽  
pp. 33-35 ◽  
Author(s):  
Joachim Jentsch
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Biological Activity ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Polypeptide Chain ◽  
Optical Rotatory Dispersion ◽  
Optical Rotatory ◽  
Surface Active ◽  
Α Helix

Melittin is the (main) toxic peptide of bee venom having a molecular weight of 2840, with a known sequence (s. fig. 1). Optical rotatory dispersion of non-crystalline melittin in aqueous solution suggests that the polypeptide chain is random, although 7% α-helix has been determined. These results are in agreement with the amino acid sequence of melittin and the assumption that the biological activity is attributable to its surface active character.

What vibrations tell about proteins

2002 ◽  
Vol 35 (4) ◽  
pp. 369-430 ◽  
Author(s):  
Andreas Barth ◽  
Christian Zscherp
Keyword(s):  
Amino Acid ◽  
Secondary Structure ◽  
Ir Spectroscopy ◽  
Reaction Mechanisms ◽  
Amino Acid Side Chain ◽  
Difference Spectroscopy ◽  
Transition Dipole ◽  
Dipole Coupling ◽  
Α Helix ◽  
Β Sheet

1. Introduction 3702. Infrared (IR) spectroscopy – general principles 3722.1 Vibrations 3722.2 Information that can be derived from the vibrational spectrum 3722.3 Absorption of IR light 3753. Protein IR absorption 3763.1 Amino-acid side-chain absorption 3763.2 Normal modes of the amide group 3814. Interactions that shape the amide I band 3824.1 Overview 3824.2 Through-bond coupling 3834.3 Hydrogen bonding 3834.4 Transition dipole coupling (TDC) 3835. The polarization and IR activity of amide I modes 3875.1 The coupled oscillator system 3875.2 Optically allowed transitions 3885.3 The infinite parallel β-sheet 3885.4 The infinite antiparallel β-sheet 3895.5 The infinite α-helix 3906. Calculation of the amide I band 3916.1 Overview 3916.2 Perturbation treatment by Miyazawa 3936.3 The parallel β-sheet 3946.4 The antiparallel β-sheet 3956.5 The α-helix 3966.6 Other secondary structures 3987. Experimental analysis of protein secondary structure 3987.1 Band fitting 3987.2 Methods using calibration sets 4017.3 Prediction quality 4038. Protein stability 4048.1 Thermal stability 4048.2 1H/2H exchange 4069. Molecular reaction mechanisms of proteins 4089.1 Reaction-induced IR difference spectroscopy 4089.2 The origin of difference bands 4099.3 The difference spectrum seen as a fingerprint of conformational change 4109.4 Molecular interpretation: strategies of band assignment 41610. Outlook 41911. Acknowledgements 42012. References 420This review deals with current concepts of vibrational spectroscopy for the investigation of protein structure and function. While the focus is on infrared (IR) spectroscopy, some of the general aspects also apply to Raman spectroscopy. Special emphasis is on the amide I vibration of the polypeptide backbone that is used for secondary-structure analysis. Theoretical as well as experimental aspects are covered including transition dipole coupling. Further topics are discussed, namely the absorption of amino-acid side-chains, 1H/2H exchange to study the conformational flexibility and reaction-induced difference spectroscopy for the investigation of reaction mechanisms with a focus on interpretation tools.

scholarly journals Antimicrobial Activity of Snake β-Defensins and Derived Peptides

Toxins ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Nancy Oguiura ◽  
Poliana Garcia Corrêa ◽  
Isabella Lemos Rosmino ◽  
Ana Olívia de Souza ◽  
Kerly Fernanda Mesquita Pasqualoto
Keyword(s):  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
Pathogenic Bacteria ◽  
Micrococcus Luteus ◽  
Peptide Sequence ◽  
Tryptophan Residue ◽  
High Antimicrobial Activity ◽  
Bacteria And Fungi ◽  
Microbroth Dilution ◽  
And Staphylococcus Aureus

β-defensins are antimicrobial peptides presenting in vertebrate animals. They participate in innate immunity, but little is known about them in reptiles, including snakes. Although several β-defensin genes were described in Brazilian snakes, their function is still unknown. The peptide sequence from these genes was deduced, and synthetic peptides (with approximately 40 amino acids and derived peptides) were tested against pathogenic bacteria and fungi using microbroth dilution assays. The linear peptides, derived from β-defensins, were designed applying the bioisosterism strategy. The linear β-defensins were more active against Escherichia coli, Micrococcus luteus, Citrobacter freundii, and Staphylococcus aureus. The derived peptides (7–14 mer) showed antibacterial activity against those bacteria and on Klebsiella pneumoniae. Nonetheless, they did not present activity against Candida albicans, Cryptococcus neoformans, Trychophyton rubrum, and Aspergillus fumigatus showing that the cysteine substitution to serine is deleterious to antifungal properties. Tryptophan residue showed to be necessary to improve antibacterial activity. Even though the studied snake β-defensins do not have high antimicrobial activity, they proved to be attractive as template molecules for the development of antibiotics.

scholarly journals The Effect of Luteolin and Luteoloside on the Secondary Structure of Lysozyme

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yu Wu ◽  
Lijian Cui ◽  
Lingling Qu ◽  
Rong Wang ◽  
Ning Chen ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Biological Activity ◽  
Secondary Structure ◽  
Raman Spectra ◽  
Active Site ◽  
Lysozyme Activity ◽  
Relative Content ◽  
Significant Difference ◽  
Α Helix

The changes of lysozyme conformation in the absence and presence of luteolin and luteoloside were investigated by spectral analysis including fluorescence, UV, CD, Raman, and ATR-FTIR, and the biological activity of lysozyme was investigated by lysozyme assay kit. The results showed that the microenvironment hydrophobicity of lysozyme increased and peptide extension decreased with the addition of luteolin or luteoloside. The α-helix of lysozyme might be influenced by luteolin or luteoloside, and its relative content had a significant difference after adding luteolin or luteoloside by the ATR-FTIR method, which was reconfirmed by CD and Raman spectra. The lysozyme activity changed obviously after adding luteolin or luteoloside. All of the conclusions above indicated the active site of lysozyme in the α-helix might be influenced by luteolin and luteoloside.

scholarly journals Secondary Structure of Human De Novo Evolved Gene Product NCYM Analyzed by Vacuum-Ultraviolet Circular Dichroism

2021 ◽  
Vol 11 ◽  
Author(s):  
Tatsuhito Matsuo ◽  
Kazuma Nakatani ◽  
Taiki Setoguchi ◽  
Koichi Matsuo ◽  
Taro Tamada ◽  
...  
Keyword(s):  
Neural Network ◽  
Circular Dichroism ◽  
Amino Acid ◽  
Secondary Structure ◽  
Vacuum Ultraviolet ◽  
De Novo ◽  
Amino Acid Level ◽  
Human Populations ◽  
Α Helix ◽  
Circular Dichroïsm

NCYM, a cis-antisense gene of MYCN, encodes a Homininae-specific protein that promotes the aggressiveness of human tumors. Newly evolved genes from non-genic regions are known as de novo genes, and NCYM was the first de novo gene whose oncogenic functions were validated in vivo. Targeting NCYM using drugs is a potential strategy for cancer therapy; however, the NCYM structure must be determined before drug design. In this study, we employed vacuum-ultraviolet circular dichroism to evaluate the secondary structure of NCYM. The SUMO-tagged NCYM and the isolated SUMO tag in both hydrogenated and perdeuterated forms were synthesized and purified in a cell-free in vitro system, and vacuum-ultraviolet circular dichroism spectra were measured. Significant differences between the tagged NCYM and the isolated tag were evident in the wavelength range of 190–240 nm. The circular dichroism spectral data combined with a neural network system enabled to predict the secondary structure of NCYM at the amino acid level. The 129-residue tag consists of α-helices (approximately 14%) and β-strands (approximately 29%), which corresponded to the values calculated from the atomic structure of the tag. The 238-residue tagged NCYM contained approximately 17% α-helices and 27% β-strands. The location of the secondary structure predicted using the neural network revealed that these secondary structures were enriched in the Homininae-specific region of NCYM. Deuteration of NCYM altered the secondary structure at D90 from an α-helix to another structure other than α-helix and β-strand although this change was within the experimental error range. All four nonsynonymous single-nucleotide polymorphisms (SNPs) in human populations were in this region, and the amino acid alteration in SNP N52S enhanced Myc-nick production. The D90N mutation in NCYM promoted NCYM-mediated MYCN stabilization. Our results reveal the secondary structure of NCYM and demonstrated that the Homininae-specific domain of NCYM is responsible for MYCN stabilization.

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

2019 ◽  
Vol 26 (3) ◽  
pp. 192-203
Author(s):  
María Verónica Húmpola ◽  
María Carolina Rey ◽  
Pablo Gabriel Spontón ◽  
Arturo Carlos Simonetta ◽  
Georgina Guadalupe Tonarelli
Keyword(s):  
Antimicrobial Activity ◽  
Secondary Structure ◽  
Mammalian Cells ◽  
Therapeutic Index ◽  
Dilution Method ◽  
Hemolysis Assay ◽  
Improved Stability ◽  
Repetitive Motif ◽  
Bacteria And Fungi ◽  
Α Helix

Background:In the last years, Antimicrobial Peptides (AMPs) and lipopeptides have received attention as promising candidates to treat infections caused by resistant microorganisms. </P><P> 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. Membrane-peptide interaction studies were performed with model phospholipid membranes mimicking those of bacterial and mammalian cells by Fluorescence Spectroscopy. The secondary structure in solution and membranes was determined by Circular Dichroism.Results:Our results showed that the resulting compounds have inhibitory activity against bacteria and fungi. The (KLFK)3 peptide showed the highest therapeutic index against bacterial and yeast strains, and the (KLFK)2 peptide conjugated with octanoic acid was the most active against yeasts. All the lipopeptides containing long-chain fatty acids (C14 or longer) were highly hemolytic at low concentrations. The antimicrobial activity of (KLFK)2 and (KLFK)3 lipopeptides was mainly associated with improved stability of the amphipathic secondary structure, which showed high contributions of α-helix in dipalmitoylphosphatidylglycerol (DPPG) vesicles.Conclusion:The repetition of the KLFK sequence and the conjugation with lipid tails allowed obtained compounds with high antimicrobial activity and low toxicity, becoming good candidates for treating infectious diseases.

scholarly journals The prediction of the conformation of membrane proteins from the sequence of amino acids

1976 ◽  
Vol 153 (3) ◽  
pp. 729-732 ◽  
Author(s):  
N M Green ◽  
M T Flanagan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Secondary Structure ◽  
Membrane Proteins ◽  
Amino Acid Sequence ◽  
Α Helix

The methods of Chou & Fasman [Biochemistry (1974) 13, 211-222, 222-245] and of Lim [J. Mol. Biol. (1974)88, 857-872, 873-894] for predicting secondary structure from amino acid sequence have been applied to five predominantly helical membrane-associated peptides. The predictions from the method of Lim (1974a,b) are consistent with the experimental observations, whereas those from Chou & Fasman (1974a,b), although not inconsistent with α-helix, favour a β-structure for several very hydrophobic regions. The results may be rationalized in terms of the effect of the solvent on the conformation of a polypeptide.

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