|
|
Mode of action of antimicrobial lipopeptides produced by Bacillus subtilis
Pinkas, Dominik ; Seydlová, Gabriela (advisor) ; Žíla, Vojtěch (referee)
Increasing bacterial resistance to classical antibiotics and emergence of multi-resistant strains impose a constant threat. Antimicrobial compounds of bacterial origin are an important source of new antibacterial therapeutic agents needed to answer this issue. Three families of lipopeptides produced by Bacillus subtilis - surfactins, fengycins and iturins represent an interesting class of such compounds. They exert a wide range of biological activities and possess a good potential for modifications and improvement of their structure and function. Lipopeptides produced by B. subtilis are surface active compounds capable of reducing surface/interface tension. The variety of their biological activities stems from their ability to insert into lipid membranes leading to disruption and permeabilization of the membrane. Specific mode of action differs between the three families but the common feature is that it is concentration dependent. First, lipopeptides induce ion leakage, pore formation and then the increasing concentration eventually causes complete solubilisation of the membrane in a detergent-like manner. In addition, surfactin can inhibit some enzymes by chelating divalent cations required for their activity. These properties make the B. subtilis lipopeptides promising compounds for commercial applications.
|
|
|
Analysis of antimicrobial peptides in venom glands of bumblebees.
Janechová, Daniela ; Cvačka, Josef (advisor) ; Monincová, Lenka (referee)
The growing resistance of bacteria to traditional antibiotics promotes the interest in finding new substances for their production. Antimicrobial peptides have comparable effect to conventional antibiotics, but a different mechanism of action and they do not provoke bacterial resistance. These peptides were characterized in all forms of multicellular organisms. Hymenoptera venom contains many biologically active substances including antimicrobial peptides. For this reason, this thesis focuses on the acquisition of antimicrobial peptide sequences from selected species of bumblebees (Bombus terrestris, B. hortorum, B. hypnorum, B. pratorum, B. lucorum, B. lapidarius, B. humilis and B. bohemicus). The isolation from the venom glands was performed by high performance liquid chromatography with reversed phases. Subsequent analysis was performed using the methods of mass spectrometry, matrix-assisted laser desorption/ionization with time of flight analyzer and electrospray ionization connected with hybrid linear ion trap analyzer with orbitrap. The sequences for the found peptides were determined by tandem mass spectrometry methods "de novo" and Edman degradation. In this work we characterized 17 sequences of peptides extracted from bumblebee venom glands for which antimicrobial activity was determined...
|
|
|
Identification of antimicrobila peptides in spider venom
Benýšek, Jakub ; Liberda, Jiří (referee) ; Tichá, Marie (advisor)
Still increasing resistance to antibiotics leads to the need to find new active compounds with antimicrobial properties. This work is focused on the occurrence, chemical and physical description, mechanism of action and biological activity of such substances, found in spider venom. The second part is focused on isolation and identification of compounds with these properties from the venom of wild bees and a one spider. A novel peptide was isolated and identified from venom of bee Trachusa byssina. This novel peptide possess antimicrobial properties and low hemolytic activity. Molecular weight was estimated to 1749,9 ? 0,1contains 16 amino acids and is amidated on its C-terminus. Its primary structure GILSVLKNLLKKHMAS-NH2 was determined by using Edman degradation and ESI-QTOF mass spektrometry.
|
|
|
Study of interaction of antimicrobial peptides with cells in culture
Kroupová, Hilda ; Stiborová, Marie (advisor) ; Votruba, Ivan (referee)
In English The thesis deals with research of novel antimicrobial peptides (AMP) Halictines (HAL-1, GMWSKILGHLIR-NH2 a HAL-2, GKWMSLLKHILK-NH2) and their structural analogs isolated from the venom of the wild bee Halictus sexcinctus. The structure and antimicrobial activity of these peptides had been described earlier [1]. The goal of this diploma thesis is to find peptide which is strongly toxic only for cancer cells and nontoxic for normal cells. Using of the fluorescent marked peptides we aimed to acquire the information about mechanism of action of the studied peptides on the cells. Using the MTT test (determination of valuation IC50), the toxicity of HAL-1 and HAL-2 and their analogs against 2 normal cell lines (Human umbilical vein endothelial cells, HUVEC, and normal rat intestinal cells, IEC) and against 2 cancer cell lines (cancer cells of suppository uterine, HeLa-S3 and cancer cells of human colorectal carcinoma, CRC SW 480) was determined. First we tested antimicrobial peptides with antimicrobial activity and low hemolytic activity. For verification the toxicity of less active analogs was also determined. We found out that the HeLa-S3 cells are the most sensitive to these peptides. The most toxic peptides (HAL-1/9, HAL-1/18, HAL-2/2) kill 50% of cells in the concentration 2,5 - 10 µM. To obtain...
|
|
| |
|
|
Characterization of organic nanoparticles with encapsulated antimicrobial peptides
Vejrostová, Petra ; Němcová, Andrea (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on characterization of particles containing encapsulated antimicrobial enzyme lysozyme. The theoretical part deals with characterization of antimicrobial peptides and their description. Further part of review was focused on lysozyme, the selected representative used in this thesis, its structure, mechanism of action and possible usage. In the experimental part the Hartree-Lowry method was used for lysozyme detection, determination of encapsulation efficiency and for detecting the amount of lysozyme released after incubation in model physiological environment and in model foods. In process of encapsulation the highest amount of lysozyme was packed into 1% chitosan particles, manually prepared alginate particles and into liposomes. During study of stability of particles in model foods as the least stable manually prepared chitosan particles were found. The released lysozyme exhibited changes probably caused by its degradation. The highest influence on particles proved 3% acetic acid. During studying the stability of the particles in artificial digestive fluids as the most unstable manually prepared chitosan particles were found, while alginate particles were the most stable. The thesis also deals with changes in antimicrobial activity of encapsulated lysozyme in prepared particles and after its application into the model environments. A gram-positive bacteria Bacillus subtilis was used in order to test the antimicrobial activity. Antimicrobial tests showed that after encapsulation antimicrobial activity of lysozyme was substantially decreased in most samples. Size and stability of prepared particles was tested using dynamic light scattering.
|
|
| |
|
| |
|
|
Chiral analysis of beta-alanyl-D,L-tyrosine and its derivatives by capillary electrophoresis with 2-hydroxypropyl-beta-cyclodextrin stereoselector
Sázelová, Petra ; Šolínová, Veronika ; Schimperková, Tereza ; Mášová, Alice ; Jiráček, Jiří ; Kašička, Václav
A new capillary electrophoretic method was developed for separation of enantiomers of antimicrobial dipeptide betha-Ala-D,L-Tyr and its derivatives using 50 mM Tris-phosphate, pH 2.50, as background electrolyte and 2-hydroxypropyl-betha-cyclodextrin at concentrations 20 – 60 mg/mL as chiral selector. In addition, association constants of complexes of the enatiomers of dipeptide betha-Ala-D,L-Tyr and its derivatives with 2-hydroxypropyl-betha-cyclodextrin chiral selector were determined.
|
|
| |
guest ::
