Güler, Günnur
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Guler, G.
Guler, Gunnur
Güler, G.
Guler, Gunnur
Güler, G.
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Email Address
gunnurguler@iyte.edu.tr
Main Affiliation
04.05. Department of Pyhsics
Status
Current Staff
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Sustainable Development Goals
1NO POVERTY
0
Research Products
2ZERO HUNGER
0
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3GOOD HEALTH AND WELL-BEING
11
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4QUALITY EDUCATION
0
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5GENDER EQUALITY
0
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6CLEAN WATER AND SANITATION
0
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7AFFORDABLE AND CLEAN ENERGY
1
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8DECENT WORK AND ECONOMIC GROWTH
0
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
1
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10REDUCED INEQUALITIES
0
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11SUSTAINABLE CITIES AND COMMUNITIES
0
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12RESPONSIBLE CONSUMPTION AND PRODUCTION
2
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13CLIMATE ACTION
1
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14LIFE BELOW WATER
0
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15LIFE ON LAND
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16PEACE, JUSTICE AND STRONG INSTITUTIONS
0
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17PARTNERSHIPS FOR THE GOALS
0
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Documents
30
Citations
555
h-index
11
Documents
29
Citations
509
Scholarly Output
25
Articles
15
Views / Downloads
3475/2899
Supervised MSc Theses
5
Supervised PhD Theses
0
WoS Citation Count
64
Scopus Citation Count
65
Patents
0
Projects
0
WoS Citations per Publication
2.56
Scopus Citations per Publication
2.60
Open Access Source
9
Supervised Theses
5
| Journal | Count |
|---|---|
| Scientific Reports | 3 |
| European Biophysics Journal with Biophysics Letters | 2 |
| Archives of Biochemistry and Biophysics | 1 |
| Biophysical Chemistry | 1 |
| Cells | 1 |
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25 results
Scholarly Output Search Results
Now showing 1 - 10 of 25
Article Citation - WoS: 1Citation - Scopus: 1Biophysical Assessment of Protein Stability in Ethanol-Stressed Environments via UV Absorption and Fluorescence Spectroscopies(Elsevier, 2026) Akyuz, Ersed; Vorob'ev, Mikhail M.; Guler, GunnurMaintaining the structure and functionality of proteins is crucial in applications ranging from food preservation to pharmaceutical formulation. Ethanol, while commonly used as a solvent and preservative, can induce structural changes in proteins depending on its concentration and the specific structure of the protein itself. This study investigates the structural effects of ethanol on three types of model proteins, namely bovine serum albumin (BSA), beta-Lactoglobulin (beta-Lg), and beta-Casein (beta-Cn), by using UV-Vis spectroscopy and fluorescence spectroscopy. The conformational responses of proteins in water-EtOH solutions of various ethanol concentrations (0-10 %, v/v) were analyzed through absorbance and emission spectral changes. At increasing ethanol concentration, UV absorption data showed distinct protein-dependent spectral changes. beta-Lg and beta-Cn exhibited strong hypochromism (an absorbance decrease of similar to 25 %) and red-shifting at 222 nm and 220 nm, respectively, indicating partial unfolding and solvent exposure of aromatic residues. BSA demonstrated subtle changes, and consistent quenching in fluorescence with a continuous blue-shifting to 330 nm, suggesting a moderate overall stability and local rearrangements in its structure. beta-Cn exhibited red-shifted fluorescence and quenching, reflecting its flexible, disordered structure and heterogeneous response to solvent conditions. Statistical analysis revealed that while fluorescence spectroscopy was highly sensitive to the intrinsic differences between proteins (p < 0.001), the ethanol-induced conformational changes were too subtle to be detected as a statistically significant treatment effect. The consistency of these trends indicates a rational underlying mechanism of interaction. This reflects the subtle nature of the effect at the tested concentrations rather than the absence of an effect. Moreover, these results unveil the protein-specific effects of ethanol and strongly emphasize the importance of solvent composition in maintaining protein integrity. Ethanol concentrations up to 5 % may offer protein stability whereas high ethanol levels (>= 5-10 %) promote structural perturbations. These results will be useful for both basic scientific research, such as biophysical studies and the advancement of optical techniques, and various industrial uses.Article Citation - WoS: 2Citation - Scopus: 2Modulating Cancer Stem Cell Characteristics in CD133+ Melanoma Cells through Hif1α, KLF4, and SHH Silencing(Amer Chemical Soc, 2025) Ozdil, Berrin; Güler, Günnur; Avci, Cigir Biray; Calik-Kocaturk, Duygu; Gorgulu, Volkan; Uysal, Aysegul; Guler, Gunnur; Aktug, HuseyinMalignant melanoma is a highly aggressive form of skin cancer, partly driven by a subset of cancer stem cells (CSCs) with remarkable capacities for self-renewal, differentiation, and resistance to therapy. In this study, we examined how silencing three key genes-Hif1 alpha, KLF4, and SHH-affects CSC characteristics. Using small interfering RNA (siRNA)-based approaches, we observed significant changes at both the gene and protein levels, shedding light on how these pathways influence melanoma progression. Our results demonstrated that silencing these genes reduces the stem-like features of CSCs. Notably, Hif1 alpha silencing triggered a marked decrease in hypoxia-related gene expression, while targeting SHH led to a reduction in Gli1, a downstream effector of SHH signaling, highlighting its potential as a therapeutic target. We also observed changes in epigenetic markers such as HDAC9 and EP300, which play crucial roles in maintaining stemness and regulating gene expression. Interestingly, these interventions appeared to reprogram CSCs, pushing them toward a phenotype distinct from both traditional CSCs and non-stem cancer cells (NCSCs). Our findings emphasize the importance of targeting key signaling pathways in melanoma CSCs and underscore the value of mimicking the tumor microenvironment in experimental models. By revealing the dynamic plasticity of melanoma CSCs, this study offers fresh insights into potential therapeutic strategies, particularly using siRNA to modulate pathways associated with tumor progression and stem cell behavior.Article Citation - WoS: 5Citation - Scopus: 5Differences and Similarities in Biophysical and Biological Characteristics Between U87 Mg Glioblastoma and Astrocyte Cells(Springer, 2023) Özdil, Berrin; Çalık Kocatürk, Duygu; Altunayar Ünsalan, Çisem; Açıkgöz, Eda; Oltulu, Fatih; Görgülü, Volkan; Uysal, Ayşegül; Öktem, Gülperi; Ünsalan, Ozan; Güler, Günnur; Aktuğ, HüseyinCurrent cancer studies focus on molecular-targeting diagnostics and interactions with surroundings; however, there are still gaps in characterization based on topological differences and elemental composition. Glioblastoma (GBM cells; GBMCs) is an astrocytic aggressive brain tumor. At the molecular level, GBMCs and astrocytes may differ, and cell elemental/topological analysis is critical for identifying potential new cancer targets. Here, we used U87 MG cells for GBMCS. U87 MG cell lines, which are frequently used in glioblastoma research, are an important tool for studying the various features and underlying mechanisms of this aggressive brain tumor. For the first time, atomic force microscopy (AFM), scanning electron microscopy (SEM) accompanied by energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) are used to report the topology and chemistry of cancer (U87 MG) and healthy (SVG p12) cells. In addition, F-actin staining and cytoskeleton-based gene expression analyses were performed. The degree of gene expression for genes related to the cytoskeleton was similar; however, the intensity of F-actin, anisotropy values, and invasion-related genes were different. Morphologically, GBMCs were longer and narrower while astrocytes were shorter and more disseminated based on AFM. Furthermore, the roughness values of these cells differed slightly between the two call types. In contrast to the rougher astrocyte surfaces in the lamellipodial area, SEM-EDS analysis showed that elongated GBMCs displayed filopodial protrusions. Our investigation provides considerable further insight into rapid cancer cell characterization in terms of a combinatorial spectroscopic and microscopic approach.Article Development and Evaluation of 177Lu-Imatinib: Radiolabeling and Cell Culture Studies(Walter de Gruyter GmbH, 2025) Ozgenc, E.; Karpuz, M.; Guler, G.; Burak, Z.; Başpainar, Y.; Gundogdu, E.A.Targeted radiopharmaceuticals offer promising approaches for cancer diagnosis and therapy. This study developed freeze-dried kit formulations of 177Lu-Imatinib (IMT) and evaluated their potential efficacy through in vitro studies. Four formulations (F1-F4) containing IMT and chelating agents were prepared and characterized via Fourier transform infrared (FTIR), ultraviolet spectrum (UV), and thermogravimetric analysis (TGA) to confirm complex formation. Biocompatibility was assessed in NIH-3T3 cells using the MTT assay. Radiolabeling with 177Lu was optimized by varying pH, incubation time, and reactant ratios. Radiochemical purity and stability were analyzed over 7 days using HPLC. Binding affinity and cytotoxicity were evaluated in MCF-7 and NIH-3T3 cells. Spectroscopic analyses confirm successful complex formation. All formulations exhibited >90% viability in NIH-3T3 cells. Optimal radiolabeling conditions (45mg IMT-chelator, pH 5, 60min incubation) yielded >90% efficiency, with stable radiolabeling for 7 days. The 177Lu-IMT-DOTA (F3) formulation showed significantly higher binding and cytotoxic effects in MCF-7 cells compared to controls. The 177Lu-IMT-DOTA (F3) kit demonstrates high radiolabeling efficiency, stability, and selective in vitro cytotoxicity toward breast cancer cells, supporting its potential as a targeted radiopharmaceutical. © 2025 Walter de Gruyter GmbH, Berlin/Boston 2025.Article Linking RNA Methylation to Structure: A Biophysical Perspective(Wiley, 2026) Akgul, Bunyamin; Guler, Gunnur; Saglam, Buket; Akkus, Onur; Akcaoz-Alasar, AzimeRecent epitranscriptomic studies show that ribonucleic acids (RNAs) are coated with an array of chemical modifications that dictate their cellular fate. Genetic, biochemical, and genomic approaches have been employed to elucidate the molecular details of RNA methylation, one of the most prevalent types of RNA modifications with significant implications for health and disease. Various biochemical approaches have been developed to identify RNA methylations both at the global and nucleotide resolution levels. However, simpler detection methods are needed to assess the global methylation status of synthetic or cellular RNAs. Although significant progress has been made in elucidating the factors involved in writing, erasing, or reading methylated epitopes or structures, the impact of these methyl moieties on the secondary structure of RNAs or macromolecular interactions remains to be fully understood. Typically, biophysical approaches, such as Fourier transformed-infrared (FT-IR) spectroscopy, circular dichroism (CD), and Raman spectroscopy, have been used to study the structures and interactions of macromolecules, including DNA and proteins. Although RNAs harbor similar chemical modifications or structure-mediated functions, the number of RNA studies that employ biophysical approaches is scarce. In this viewpoint article, we present a biophysical perspective that links RNA methylation to structure and propose that FT-IR analyses can be employed to examine global changes in the abundance of cellular RNA m(6)A marks. Additionally, we discuss the potential applications of biophysical approaches that may be employed to gain insight into methylation-mediated changes in RNA structures.Conference Object Reagent-Free Urea Determination From Hemodialysis Fluid: Development of FT-IR Spectroscopic Strategies(Springer, 2025) Akyuz, Ersed; Tanrisev, Mehmet; Guler, GunnurBook Part Citation - WoS: 5Citation - Scopus: 4Surface Characterization Techniques(Wiley-v C H Verlag Gmbh, 2017) Erdogan, Gokhan; Guler, Gunnur; Kilic, Tugba; Kilic, Duygu O.; Erdogan, Beyhan; Tosun, Zahide; Karaman, MustafaArticle Citation - WoS: 11Citation - Scopus: 13Proteolysis of Micellar Β-Casein by Trypsin: Secondary Structure Characterization and Kinetic Modeling at Different Enzyme Concentrations(MDPI, 2023) Vorob’ev, Mikhail M.; Açıkgöz, Burçin Dersu; Güler, Günnur; Golovanov, Andrey V.; Sinitsyna, Olga V.Tryptic proteolysis of protein micelles was studied using β-casein (β-CN) as an example. Hydrolysis of specific peptide bonds in β-CN leads to the degradation and rearrangement of the original micelles and the formation of new nanoparticles from their fragments. Samples of these nanoparticles dried on a mica surface were characterized by atomic force microscopy (AFM) when the proteolytic reaction had been stopped by tryptic inhibitor or by heating. The changes in the content of β-sheets, α-helices, and hydrolysis products during proteolysis were estimated by using Fourier-transform infrared (FTIR) spectroscopy. In the current study, a simple kinetic model with three successive stages is proposed to predict the rearrangement of nanoparticles and the formation of proteolysis products, as well as changes in the secondary structure during proteolysis at various enzyme concentrations. The model determines for which steps the rate constants are proportional to the enzyme concentration, and in which intermediate nano-components the protein secondary structure is retained and in which it is reduced. The model predictions were in agreement with the FTIR results for tryptic hydrolysis of β-CN at different concentrations of the enzyme.Article Citation - WoS: 2Citation - Scopus: 2Effect of Mirna Administration on Non-Small Cell Lung Cancer Cells Studied by Cellular Viability Assay and Atr-Ftir Spectroscopy Combined With Multivariate Data-Analysis(Elsevier, 2025) Dagdeviren, Melih; Guler, Gunnur; Guler, Egemen Erdem; Un, Cemal; Karabay-Yavasoglu, Nefise UlkuMicroRNAs (miRNAs), small non-coding RNAs, play a significant role in the regulation of gene expression by various mechanisms. Some miRNAs such as hsa-miR-145 (mir145), hsa-let-7a-1 (let7), hsa-miR-155 (mir155), and hsa-miR-29b (mir29b) are expressed at low levels in cancers and associated with proliferation, metastasis, invasion and apoptosis. In the current study, we aimed to investigate the effect of selected synthetic miRNAs and their combinations on the non-small cell lung cancer (NSCLC) cells (A549) by following the cell viability profile and alterations in the cellular biomolecules with biophysical features. After administration of commercial miRNAs and their various combinations to A549 cell line, each group was analyzed with cell viability assay and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy combined with unsupervised multivariate analysis. Bioinformatics analysis was also performed to detect and to classify the target human genes obtained from the mirDB database. According to the cell viability results, the "mir29b + let7" combination and "mir155" significantly decreased the cancer cell viability whereas the "mir145 + mir29b" and "mir155 + mir145" combinations dramatically increased the cancer cell viability when compared to the control cells. The FTIR data revealed that administration of the "mir155", "mir29b + let7 + mir155", and "mir29b + let7" combinations caused a decrease in the contents of proteins, lipids and nucleic acids in A549 cells. This study suggests that those miRNA combinations might be potential targets for vaccines or miRNA-based therapies that can restore the miRNA activity and thus should be further evaluated to combat lung cancer with miRNA technology.Article Citation - WoS: 4Citation - Scopus: 3An Investigation of Rna Methylations With Biophysical Approaches in a Cervical Cancer Cell Model(Mdpi, 2024) Saglam, Buket; Akkus, Onur; Akcaoz-Alasar, Azime; Ceylan, Cagatay; Guler, Gunnur; Akgul, BunyaminRNA methylation adds a second layer of genetic information that dictates the post-transcriptional fate of RNAs. Although various methods exist that enable the analysis of RNA methylation in a site-specific or transcriptome-wide manner, whether biophysical approaches can be employed to such analyses is unexplored. In this study, Fourier-transform infrared (FT-IR) and circular dichroism (CD) spectroscopy are employed to examine the methylation status of both synthetic and cellular RNAs. The results show that FT-IR spectroscopy is perfectly capable of quantitatively distinguishing synthetic m(6)A-methylated RNAs from un-methylated ones. Subsequently, FT-IR spectroscopy is successfully employed to assess the changes in the extent of total RNA methylation upon the knockdown of the m(6)A writer, METTL3, in HeLa cells. In addition, the same approach is shown to accurately detect reduction in total RNA methylation upon the treatment of HeLa cells with tumor necrosis factor alpha (TNF-alpha). It is also demonstrated that m(1)A and m(6)A methylation induce quite a distinct secondary structure on RNAs, as evident from CD spectra. These results strongly suggest that both FT-IR and CD spectroscopy methods can be exploited to uncover biophysical properties impinged on RNAs by methyl moieties, providing a fast, convenient and cheap alternative to the existing methods.
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