| | SLO | ENG | Piškotki in zasebnost

Večja pisava | Manjša pisava

Iskanje po katalogu digitalne knjižnice Pomoč

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


1 - 10 / 38
Na začetekNa prejšnjo stran1234Na naslednjo stranNa konec
1.
Določevanje vpliva multivalentnih fosfatnih in sulfonatnih pomožnih snovi na agregacijo proteinov za uporabo v biofarmacevtskih izdelkih
Tjaša Krepek, 2024, diplomsko delo

Opis: V zadnjih desetletjih se je biofarmacevtska industrija osredotočila na razvoj bioloških zdravil. Večinoma gre za kompleksne beljakovinske molekule, ki so zahtevne in drage za izdelavo ter imajo omejen rok uporabe, ki je posledica nestabilnosti samih beljakovin. Na nestabilnost proteinov in agregacijo lahko vplivamo z dodatkom malih molekul in pomožnih snovi kot so površinsko aktivne snovi, pufri, sladkorji, soli itd., ki se na protein neposredno vežejo in ga tako stabilizirajo. Dosedanje raziskave so že preučile vpliv adenozin tripolifosfata in tripoli fosfata na agregacijo biofarmacevtskih proteinov, zato smo v diplomskem delu preučili še vpliv petih drugih že priznanih fosfatnih ionov in za primerjavo izbrali še deset ATP- ju podobnih sulfonatnih spojin, saj so polifosfati nagnjeni k hidrolizi in posledično niso primerni za uporabo kot pomožne snovi. Uporabili smo modelni protein lizocim kokošjega beljaka ter preverjali vpliv pomožnih snovi pri različnih koncentracijah na kinetiko agregacije proteina, ki smo jo spremljali z UV- Vis spektrometrijo. S pomočjo UV-Vis spektrometrije smo opravili tudi presejalni test pomožnih snovi na agregacijo proteina in izračunali delež monomernega proteina. Ugotovili smo, da fosfatne pomožne snovi in večina sulfonatnih učinkovito zaščitijo in stabilizirajo protein in ga tako zaščitijo pred agregacijo kot je ta podvržen temperaturnemu stresu ter ga zaščitijo pred agregacijo v daljšem časovnem obdobju, prav tako tudi zmanjšajo delež monomernega proteina v vzorcu. Preverili smo tudi vpliv pomožnih snovi na agregacijo delno razvitih beljakovin, kar smo dosegli z dodatkom ditiotreitola ali DTT, ki cepi disulfidne mostičke v beljakovini. V povprečju se je izkazalo, da dajejo boljše rezultate fosfatne pomožne snovi in ne sulfonatne. Najboljše rezultate sta med pomožnimi snovmi dala ATP in TPP, preostale pomožne snovi pa dale primerljive rezultate.
Ključne besede: protein, agregacija, pomožne snovi, fosfati, sulfonati, fazni diagram
Objavljeno v DKUM: 01.10.2024; Ogledov: 0; Prenosov: 12
.pdf Celotno besedilo (4,50 MB)

2.
Preučevanje interakcij med tanini in lizocimom
Anja Zaverla, 2024, diplomsko delo

Opis: Razvoj odpornosti bakterij na antibiotike je eden izmed večjih izzivov človeštva, ki zahtevajo tako iskanje novih protibakterijskih učinkovin, kot tudi izboljšanih načinov uporabe protibakterijskih sredstev. Raziskovalci nove protibakterijske učinkovine iščejo tudi med naravnimi spojinami s protimikrobnimi in protibakterijskimi učinki. Rastline vsebujejo tanine, ki so polifenolni sekundarni metaboliti, ki jih raziskujemo zaradi njihovih številnih potencialnih za zdravje ugodnih učinkov. Glede na njihovo kemijsko strukturo jih delimo na proantocianidine (kondenzirane tanine) in hidrolizirajoče tanine. Slednji se nadalje razdelijo na dve glavni podskupini (galotanin in elagitanini). V diplomskem delu smo proučevali vezavo elagitaninov na lizocim – modelni protein. Po dializi v pufru s pH = 5 smo lizocim titrirali z galno kislino, metil galatom in veskalaginom. Opazovali smo, kako prisotnost elagitaninov vpliva na fluorescenco lizocima. Vpliv dodatka taninov na sekundarno strukturo lizocima smo opazovali s cirkularnim dikroizmom (CD-spektroskopija), medtem ko smo termodinamiko vezave opazovali z izotermno titracijsko kalorimetrijo (ITC). Z opazovanjem temperaturne odvisnosti fluorescenčnega spektra lizocima smo ugotovili, da prisotnost taninov ne vpliva na temperaturo tališča proteina. S pomočjo Stern-Volmerjeve enačbe ob upoštevanju učinka notranjega filtra smo poskusili pridobiti konstante vezave taninov na lizocim. S CD-spektroskopijo smo ugotovili, da ima veskalagin večji vpliv na denaturacijo proteina, kot metil galat in galna kislina. Ugotovili smo, da je interakcija veskalagina in lizocima mnogo bolj eksotermna, kot interakcija metil galata ali galne kisline z lizocimom. Poleg tega smo z ITC-jem potrdili, da gre pri interakcijah taninov z lizocimom za razmeroma šibke interakcije.
Ključne besede: elagitanini, protein, konstanta vezave, sekundarna struktura, spektroskopija, termodinamični parametri vezave
Objavljeno v DKUM: 17.09.2024; Ogledov: 0; Prenosov: 22
.pdf Celotno besedilo (4,11 MB)

3.
Study of V[sub]2CT[sub]x-MXene Based Immunosensor for Sensitive Label-Free Impedimetric Detection of SARS-CoV-2 Spike Protein
Nikola Tasić, Ivan Konjević, Alnilan Cristina Barros Lobato, Dino Metarapi, Matjaž Finšgar, Filipa M. Oliveira, Zdeněk Sofer, Rui Gusmão, Xueji Zhang, Samo B. Hočevar, 2024, izvirni znanstveni članek

Opis: Rapid and reliable immunosensing is undoubtedly one of the priorities in the efficient management and combat against a pandemic, as society has experienced with the SARS-CoV-2 outbreak; simple and cost-effective sensing strategies are at the forefront of these efforts. In this regard, 2D-layered MXenes hold great potential for electrochemical biosensing due to their attractive physicochemical properties. Herein, we present a V$_2$CT$_x$ MXene-based sensing layer as an integral part of a label-free immunosensor for sensitive and selective detection of the SARS-CoV-2 spike protein. The sensor was fabricated on a supporting screen-printed carbon electrode using Nafion as an immobilizing agent for MXene and glutaraldehyde, the latter enabling effective binding of protein A for further site-oriented immobilization of anti-SARS-CoV-2 antibodies. A thorough structural analysis of the sensor architecture was carried out, and several key parameters affecting the fabrication and analytical performance of the immunosensor were investigated and optimized. The immunosensor showed excellent electroanalytical performance in combination with an impedimetric approach and exhibited a low detection limit of only 45 fM SARS-CoV-2 spike protein. Its practical applicability was successfully demonstrated by measuring the spike protein in a spiked artificial nasopharyngeal fluid sample.
Ključne besede: imunosenzorji, polprevodniške nanostrukture, proteini, spike protein, immunosensors, SARS-CoV-2, V2CTxMXene
Objavljeno v DKUM: 29.08.2024; Ogledov: 42; Prenosov: 2
URL Povezava na celotno besedilo

4.
Novel magnetic iron oxide-dextran sulphate nanocomposites as potential anticoagulants: Investigating interactions with blood components and assessing cytotoxicity
Olivija Plohl, Lidija Fras Zemljič, Boštjan Vihar, Alenka Vesel, Sašo Gyergyek, Uroš Maver, Irena Ban, Matej Bračič, 2024, izvirni znanstveni članek

Opis: Examining the critical role of anticoagulants in medical practice, particularly their central function in preventing abnormal blood clotting, is of the utmost importance. However, the study of interactions between blood proteins and alternative anticoagulant nano-surfaces is still understood poorly. In this study, novel approach involving direct functionalisation of magnetic iron oxide nanoparticles (MNPs) as carriers with sulphated dextran (s-dext) is presented, with the aim of evaluating the potential of magnetically-responsive MNPs@s-dext as anticoagulants. The physicochemical characterisation of the synthesised MNPs@s-dext includes crystal structure analysis, morphology study, surface and electrokinetic properties, thermogravimetric analysis and magnetic properties` evaluation, which confirms the successful preparation of the nanocomposite with sulfonate groups. The anticoagulant potential of MNPs@s-dext was investigated using a standardised activated partial thromboplastin time (APTT) test and a modified APTT test with a quartz crystal microbalance with dissipation (QCM-D) which confirmed the anticoagulant effect. Time-resolved solid-liquid interactions between the MNPs@s-dext and model blood proteins bovine serum albumin and fibrinogen were also investigated, to gain insight into their hemocompatibility, and revealed protein-repellence of MNPs@s-dext against blood proteins. The study also addressed comprehensive cytotoxicity studies of prepared nanocomposites, and provided valuable insights into potential applicability of MNPs@s-dext as a promising magnetic anticoagulant in biomedical contexts.
Ključne besede: dextran sulphate, magnetic nanoparticles, blood protein interactions, clot formation, anticoagulants, cytotoxicity studies
Objavljeno v DKUM: 25.07.2024; Ogledov: 107; Prenosov: 15
.pdf Celotno besedilo (892,02 KB)
Gradivo ima več datotek! Več...

5.
Droplet-based screening of phosphate transfer catalysis reveals how epistasis shapes MAP kinase interactions with substrates
Remkes A. Scheele, Laurens H. Lindenburg, Maya Petek, Markus Schober, Kevin N. Dalby, Florian Hollfelder, 2022, izvirni znanstveni članek

Opis: The combination of ultrahigh-throughput screening and sequencing informs on function and intragenic epistasis within combinatorial protein mutant libraries. Establishing a droplet-based, in vitro compartmentalised approach for robust expression and screening of protein kinase cascades (>107 variants/day) allowed us to dissect the intrinsic molecular features of the MKK-ERK signalling pathway, without interference from endogenous cellular components. In a six-residue combinatorial library of the MKK1 docking domain, we identified 29,563 sequence permutations that allow MKK1 to efficiently phosphorylate and activate its downstream target kinase ERK2. A flexibly placed hydrophobic sequence motif emerges which is defined by higher order epistatic interactions between six residues, suggesting synergy that enables high connectivity in the sequence landscape. Through positive epistasis, MKK1 maintains function during mutagenesis, establishing the importance of co-dependent residues in mammalian protein kinase-substrate interactions, and creating a scenario for the evolution of diverse human signalling networks.
Ključne besede: protein, epistasis, catalysis, phosphate transfer, MAP kinase
Objavljeno v DKUM: 04.07.2024; Ogledov: 104; Prenosov: 10
.pdf Celotno besedilo (2,42 MB)
Gradivo ima več datotek! Več...

6.
Effects of atrial fibrillation on the human ventricle
Steffen Pabel, Maria Knierim, Thea Stehle, Felix Alebrand, Michael Paulus, Marcel Sieme, Melissa Herwig, Friedrich Barsch, Thomas Körtl, Arnold Pöppl, Simon Sedej, 2022, izvirni znanstveni članek

Opis: Rationale: Atrial fibrillation (AF) and heart failure often coexist, but their interaction is poorly understood. Clinical data indicate that the arrhythmic component of AF may contribute to left ventricular (LV) dysfunction. Objective: This study investigates the effects and molecular mechanisms of AF on the human LV. Methods and results: Ventricular myocardium from patients with aortic stenosis and preserved LV function with sinus rhythm or rate-controlled AF was studied. LV myocardium from patients with sinus rhythm and patients with AF showed no differences in fibrosis. In functional studies, systolic Ca2+ transient amplitude of LV cardiomyocytes was reduced in patients with AF, while diastolic Ca2+ levels and Ca2+ transient kinetics were not statistically different. These results were confirmed in LV cardiomyocytes from nonfailing donors with sinus rhythm or AF. Moreover, normofrequent AF was simulated in vitro using arrhythmic or rhythmic pacing (both at 60 bpm). After 24 hours of AF-simulation, human LV cardiomyocytes from nonfailing donors showed an impaired Ca2+ transient amplitude. For a standardized investigation of AF-simulation, human iPSC-cardiomyocytes were tested. Seven days of AF-simulation caused reduced systolic Ca2+ transient amplitude and sarcoplasmic reticulum Ca2+ load likely because of an increased diastolic sarcoplasmic reticulum Ca2+ leak. Moreover, cytosolic Na+ concentration was elevated and action potential duration was prolonged after AF-simulation. We detected an increased late Na+ current as a potential trigger for the detrimentally altered Ca2+/Na+-interplay. Mechanistically, reactive oxygen species were higher in the LV of patients with AF. CaMKII (Ca2+/calmodulin-dependent protein kinase IIδc) was found to be more oxidized at Met281/282 in the LV of patients with AF leading to an increased CaMKII activity and consequent increased RyR2 phosphorylation. CaMKII inhibition and ROS scavenging ameliorated impaired systolic Ca2+ handling after AF-simulation. Conclusions: AF causes distinct functional and molecular remodeling of the human LV. This translational study provides the first mechanistic characterization and the potential negative impact of AF in the absence of tachycardia on the human ventricle.
Ključne besede: atrial fibrillation, calcium-calmodulin-dependent protein kinase type 2, excitation contraction coupling, heart failure, oxidative stress
Objavljeno v DKUM: 28.06.2024; Ogledov: 115; Prenosov: 8
.pdf Celotno besedilo (5,82 MB)
Gradivo ima več datotek! Več...

7.
8.
9.
Bioactive functional nanolayers of chitosan-lysine surfactant with single- and mixed-protein-repellent and antibiofilm properties for medical implants
Urban Ajdnik, Lidija Fras Zemljič, Olivija Plohl, Lourdes Pérez, Janja Trček, Matej Bračič, Tamilselvan Mohan, 2021, izvirni znanstveni članek

Opis: Medical implant-associated infections resulting from biofilm formation triggered by unspecific protein adsorption arethe prevailing cause of implant failure. However, implant surfaces rendered with multifunctional bioactive nanocoatings offer apromising alternative to prevent the initial attachment of bacteria and effectively interrupt biofilm formation. The need to researchand develop novel and stable bioactive nanocoatings for medical implants and a comprehensive understanding of their properties incontact with the complex biological environment are crucial. In this study, we developed an aqueous stable and crosslinker-freepolyelectrolyte−surfactant complex (PESC) composed of a renewable cationic polysaccharide, chitosan, a lysine-based anionicsurfactant (77KS), and an amphoteric antibiotic, amoxicillin, which is widely used to treat a number of infections caused by bacteria.We successfully introduced the PESC as bioactive functional nanolayers on the“model”and“real”polydimethylsiloxane (PDMS)surfaces under dynamic and ambient conditions. Besides their high stability and improved wettability, these uniformly depositednanolayers (thickness: 44−61 nm) with mixed charges exhibited strong repulsion toward three model blood proteins (serumalbumin,fibrinogen, andγ-globulin) and their competitive interactions in the mixture in real-time, as demonstrated using a quartzcrystal microbalance with dissipation (QCM-D). The functional nanolayers with a maximum negative zeta potential (ζ:−19 to−30mV at pH 7.4), water content (1628−1810 ng cm−2), and hydration (low viscosity and elastic shear modulus) correlated with themass, conformation, and interaction nature of proteins. In vitro antimicrobial activity testing under dynamic conditions showed thatthe charged nanolayers actively inhibited the growth of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcusaureus) bacteria compared to unmodified PDMS. Given the ease of fabrication of multifunctional and charged biobased coatingswith simultaneous protein-repellent and antimicrobial activities, the limitations of individual approaches could be overcome leadingto a better and advanced design of various medical devices (e.g., catheters, prosthetics, and stents).
Ključne besede: silicone implants, protein-repellent, antimicrobial, chitosan, lysine, bioactive coatings, adsorption, QCM-D
Objavljeno v DKUM: 15.04.2024; Ogledov: 266; Prenosov: 16
.pdf Celotno besedilo (4,24 MB)
Gradivo ima več datotek! Več...

10.
Iskanje izvedeno v 0.18 sek.
Na vrh
Logotipi partnerjev Univerza v Mariboru Univerza v Ljubljani Univerza na Primorskem Univerza v Novi Gorici