Korkmaz Özkan, Filiz

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Profile URL
https://hdl.handle.net/20.500.14411/6821
Name Variants
Korkmaz Ozkan,Filiz
K.,Filiz
F.,Korkmaz Ozkan
Filiz, Korkmaz Özkan
Korkmaz Ozkan,F.
K.Ö.Filiz
Korkmaz Özkan,F.
K. O. Filiz
Korkmaz F.
F.,Korkmaz Özkan
F., Korkmaz Ozkan
Filiz, Korkmaz Ozkan
Filiz Korkmaz Özkan
F., Korkmaz Özkan
Korkmaz Ozkan, Filiz
Korkmaz Özkan, Filiz
K. Ö. Filiz
K., Filiz
Özkan, Filiz Korkmaz
Korkmaz, Filiz
Job Title
Profesör Doktor
Email Address
filiz.korkmaz@atilim.edu.tr
Main Affiliation
Physics Group
Status
Website
https
ORCID ID
0000-0003-3512-3521
Scopus Author ID
8664101000
Turkish CoHE Profile ID
Google Scholar ID
4NU4lXwAAAAJ
WoS Researcher ID
2752134

Sustainable Development Goals

NO POVERTY1
NO POVERTY
0
Research Products
ZERO HUNGER2
ZERO HUNGER
0
Research Products
GOOD HEALTH AND WELL-BEING3
GOOD HEALTH AND WELL-BEING
3
Research Products
QUALITY EDUCATION4
QUALITY EDUCATION
0
Research Products
GENDER EQUALITY5
GENDER EQUALITY
0
Research Products
CLEAN WATER AND SANITATION6
CLEAN WATER AND SANITATION
3
Research Products
AFFORDABLE AND CLEAN ENERGY7
AFFORDABLE AND CLEAN ENERGY
0
Research Products
DECENT WORK AND ECONOMIC GROWTH8
DECENT WORK AND ECONOMIC GROWTH
0
Research Products
INDUSTRY, INNOVATION AND INFRASTRUCTURE9
INDUSTRY, INNOVATION AND INFRASTRUCTURE
0
Research Products
REDUCED INEQUALITIES10
REDUCED INEQUALITIES
0
Research Products
SUSTAINABLE CITIES AND COMMUNITIES11
SUSTAINABLE CITIES AND COMMUNITIES
0
Research Products
RESPONSIBLE CONSUMPTION AND PRODUCTION12
RESPONSIBLE CONSUMPTION AND PRODUCTION
0
Research Products
CLIMATE ACTION13
CLIMATE ACTION
0
Research Products
LIFE BELOW WATER14
LIFE BELOW WATER
0
Research Products
LIFE ON LAND15
LIFE ON LAND
2
Research Products
PEACE, JUSTICE AND STRONG INSTITUTIONS16
PEACE, JUSTICE AND STRONG INSTITUTIONS
0
Research Products
PARTNERSHIPS FOR THE GOALS17
PARTNERSHIPS FOR THE GOALS
0
Research Products
Documents

24

Citations

665

h-index

9

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Documents

0

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Scholarly Output

27

Articles

22

Views / Downloads

97/567

Supervised MSc Theses

4

Supervised PhD Theses

0

WoS Citation Count

600

Scopus Citation Count

619

Patents

0

Projects

0

WoS Citations per Publication

22.22

Scopus Citations per Publication

22.93

Open Access Source

9

Supervised Theses

4

JournalCount
Scientific Reports4
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy2
Physica B: Condensed Matter2
Archives of Biochemistry and Biophysics2
Journal of Biomolecular Structure and Dynamics1
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Now showing 1 - 7 of 7
  • Thumbnail Image
    Article
    Citation - WoS: 9
    Citation - Scopus: 9
    Urinalysis of Individuals With Renal Hyperfiltration Using Atr-Ftir Spectroscopy
    (Nature Portfolio, 2022) Kurultak, Ilhan; Sarigul, Neslihan; Kodal, Nil Su; Korkmaz, Filiz
    Abnormal increased glomerular filtration rate (GFR), otherwise known as renal hyperfiltration (RHf), is associated with an increased risk of chronic kidney disease and cardiovascular mortality. Although it is not considered as a disease alone in medicine today, early detection of RHf is essential to reducing risk in a timely manner. However, detecting RHf is a challenge since it does not have a practical biochemical marker that can be followed or quantified. In this study, we tested the ability of ATR-FTIR spectroscopy to distinguish 17 individuals with RHf (hyperfiltraters; RHf (+)), from 20 who have normal GFR (normofiltraters; RHf(-)), using urine samples. Spectra collected from hyperfiltraters were significantly different from the control group at positions 1621, 1390, 1346, 933 and 783/cm. Intensity changes at these positions could be followed directly from the absorbance spectra without the need for pre-processing. They were tentatively attributed to urea, citrate, creatinine, phosphate groups, and uric acid, respectively. Using principal component analysis (PCA), major peaks of the second derivative forms for the classification of two groups were determined. Peaks at 1540, 1492, 1390, 1200, 1000 and 840/cm were significantly different between the two groups. Statistical analysis showed that the spectra of normofiltraters are similar; however, those of hyperfiltraters show diversity at multiple positions that can be observed both from the absorbance spectra and the second derivative profiles. This observation implies that RHf can simultaneously affect the excretion of many substances, and that a spectroscopic analysis of urine can be used as a rapid and non-invasive pre-screening tool.
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    Article
    Citation - WoS: 32
    Citation - Scopus: 32
    Urine Analysis Using Ftir Spectroscopy: a Study on Healthy Adults and Children
    (Wiley-v C H verlag Gmbh, 2021) Sarigul, Neslihan; Kurultak, Ilhan; Gokceoglu, Arife Uslu; Korkmaz, Filiz; Uslu Gökceoğlu, Arife
    Urine spectra from 108 healthy volunteers are studied by attenuated total refraction-Fourier transform infrared (ATR-FTIR) spectroscopy. The spectral features are correlated with observable urine components. The variation of spectra within a healthy population is quantified and a library of reference spectra is constructed. Using the band assignments, these spectra are compared with both age-wise and gender-wise. Children show the least intensity variations compared to both adult groups. Young adults show the highest variation, particularly in the 1650 to 1400 cm(-1) and 1200 to 900 cm(-1) regions. These results indicate the importance of the size of the control group in comparative studies utilizing FTIR. Age-wise comparisons reveal that phosphate and sulfate excretion decreases with age, and that the variance of phosphate among individuals is higher with adults. As for gender-wise comparisons, females show a slightly higher citrate content at 1390 cm(-1) regardless of the age and they show a higher variance in the 1200 to 1000 cm(-1) region when compared to men.
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    Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Investigations of Ph-Dependent Dynamic Properties of Ompg-16sl, an Outer Membrane Protein G Mutant by Atr-Ftir Spectroscopy
    (Elsevier, 2022) Yilmaz, Irem; Korkmaz, Filiz
    In this paper, the dynamic properties of outer membrane protein G mutant (OmpG-16SL) are investigated with ATR-FTIR spectroscopy. While OmpG-WT has 14 beta-strands in its structure, the mutant is designed to have 16 beta-strands with the intention of creating an enlarged pore. Loop L6 is elongated by introducing six residues, two of which are negatively charged. The solvent accessibility of the OmpG-16SL mutant is compared with WT and a previously reported mutant OmpG-16S by tracking the H-1/H-2 exchange kinetics in acidic and neutral buffer conditions. The exchange kinetics and dynamics in the fast and slow exchange phases are separately investigated using the 2DCOS technique, which enables the tracking of the structural changes at each phase of the exchange process. The results suggest that the mutant OmpG-16SL is equally exposed to buffer in both acidic and neutral pH conditions. Additionally, the time range in the fast phase is very short - one-tenth of that for WT - and most of the exchange is completed in this phase. This fast exchange within minutes is also indicative of the presence of highly flexible and/or unstructured regions. In all, the fast exchange rates independent of the buffer pH justify the assumption that there is an altered interaction among the charged residues, which leads to a steadily-open pore. The role of the side-chain interactions within the pore and between the loops involving the loop L6 is also discussed.
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    Article
    Web Server-Based Structure Prediction as a Supplementary Tool for Basic and Acidic Fgf Secondary Structure Analysis Using Ftir Spectroscopy and a Case Study Comparing Curve-Fit With the Model-Based Structure Inspection of the Ftir Data
    (DergiPark, 2023) Korkmaz,F.; Mollaoglu,A.; Adiguzel,Y.
    Fourier Transform Infrared (FTIR) spectroscopy can provide relative proportion of secondary structure elements in a protein. However, extracting this information from the Amide I band area of an FTIR spectrum is difficult. In addition to experimental methods, several protein secondary structure prediction algorithms serving on the Web can be used as supplementary tools requiring only protein amino acid sequences as inputs. In addition, web-server based docking tools can provide structure information when proteins are mixed and potentially interacting. Accordingly, we aimed to utilize web-server based structure predictors in fibroblast growth factor (FGF) protein structure determination through the FTIR data. Seven such predictors were selected and tested on basic FGF (bFGF) protein, to predict FGF secondary structure. Results were compared to available structure-files deposited in the Protein Data Bank (PDB). Then, FTIR spectra of bFGF and the acidic form of the protein with 50 folds more bovine serum albumin as carrier protein (1FGFA/50BSA) were collected. Optimized Amide I curve-fit parameters of bFGF with low (<5) root mean square deviation (RMSD) in the PDB data and the predictions were obtained. Those parameters were applied in curve-fitting of 1FGFA/50BSA data. Secondary structure was inspected also through applying models derived from the previously established methods. Results of model-based secondary structure estimation from FTIR data were compared with secondary structure calculated as 1 part contribution from 1FGFA/1BSA complex and 49 parts contribution from BSA. Complex structure was obtained through docking. RMSD in the PDB data and the predictions were respectively 3.05 and 2.39 with the optimized parameters. Those parameters did not work well for the 1FGFA/50BSA data. Models are better in this case, wherein one model (Model-1’) with the lowest average RMSD has 8.38 RMSD in the bFGF and 4.78 RMSD in the 1FGFA/50BSA structures. Model-based secondary structure predictions are better for determining bFGF and 1FGFA/50BSA secondary structures through the curve-fit approach that we followed, under non-optimal conditions like protein/BSA mixtures. Web servers can assist experimental studies investigating structures with unknown structures. Any web-based structure prediction supporting the experimental results would be enforcing the findings, but the unsupported results would not necessarily falsify the experimental data. © (2023), (DergiPark). All rights reserved.
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    Article
    Author Correction: Using Urine Ftir Spectra To Screen Autism Spectrum Disorder
    (Nature Portfolio, 2024) Sarigul, Neslihan; Bozatli, Leyla; Kurultak, Ilhan; Korkmaz, Filiz
    [No Abstract Available]
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    Article
    Simultaneous Removal of Setazol Navy Blue and Cr(vi) by Mixed Microbial Culture Isolated From the Çubuk Stream
    (Springer int Publ Ag, 2024) Gunduz, A. Irem; Erkoc, Esra; Korkmaz, Filiz; Kilic, Nur Kocberber
    Water samples taken from the & Ccedil;ubuk Stream (Ankara, Turkey) were inoculated into nutrient broth media containing Setazol Navy Blue SBG (SNB), an organic pollutant, and heavy metal Cr(VI), an inorganic pollutant, to obtain a pollutant-resistant mixed microbial culture. Experiments were conducted with this culture to remove SNB and heavy metal. The optimum conditions, where the mixed bacterial culture removed the pollutants most effectively, were determined, showing that the highest capacity for removal took place at pH 8 with removal percentages 96.3% for Cr(VI) and 78.5% for SNB. In media with 50.4 mg/L SNB and 9.7 mg/L Cr(VI), the SNB removal was 87.3%, and the Cr(VI) removal was 96.6% at the end of the 7-day incubation period. The highest removal was observed with a biomass concentration of 8% (v/v) of mixed culture [50 mg/L SNB dye+25 mg/L Cr(VI)]. The removal was 100% for both Cr(VI) and the SNB dye. The bacteria with the highest removal were isolated and identified using 16S rDNA gene sequence analysis as Microbacterium oxydans and Leucobacter aridicollis. The role of various functional groups and the structures of the microorganisms that might be involved in the removal mechanisms were discussed using their FTIR spectra. This report is the first study that investigates a mixed bacterial culture and pure cultures (M. oxydans and L. aridicollis) isolated from that mixed culture, removing both SNB and Cr(VI) simultaneously.
  • Thumbnail Image
    Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Structural Properties of an Engineered Outer Membrane Protein G Mutant, Ompg-16sl, Investigated With Infrared Spectroscopy
    (Taylor & Francis inc, 2020) Yilmaz, Irem; Yildiz, Ozkan; Korkmaz, Filiz
    The structural and functional differences between wild type (WT) outer membrane protein G and its two mutants are investigated with Fourier transform infrared spectroscopy. Both mutants have a long extension to the primary sequence to increase the number of beta-strands from 14 (wild type) to 16 in an attempt to enlarge the pore diameter. The comparison among proteins is made in terms of pH-dependent conformational changes and thermal stability. Results show that all proteins respond to pH change but at different degrees. At acidic environment, all proteins contain the same number of residues participated in beta-sheet structure. However, at neutral pH, the mutants have less ordered structure compared to WT porin. Thermal stability tests show that mutants differ significantly from WT porin at neutral pH. Although the transition temperature is directly proportional with the amount of beta-sheet content, the changes in the pre-transition phase that pave the way to structural breakdown are shown to involve interactions among charged residues by two-dimensional correlation spectroscopy analysis. Results of the analysis show that side chain interactions play an active role under increasing temperature. Both mutants have more unordered secondary structure but they respond to pH change in tertiary structure level. Findings of this study provided deeper insight on the active players in structural stability of the WT porin. Communicated by Ramaswamy H. Sarma