Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 2Citation - Scopus: 2Gas Phase Fragmentation Behavior of Proline in Macrocyclic B7 Ions(American Chemical Society, 2023) Taşoğlu, Çağdaş; Arslanoğlu, Alper; Yalçın, TalatThefragmentation characteristics of b (7) ionsproduced from proline-containing heptapeptides have been studiedin detail. The study has utilized the following C-terminally amidatedmodel peptides: PA(6), APA(5), A(2)PA(4), A(3)PA(3), A(4)PA(2), A(5)PA, A(6)P, PYAGFLV, PAGFLVY, PGFLVYA, PFLVYAG,PLVYAGF, PVYAGFL, YPAGFLV, YAPGFLV, YAGPFLV, YAGFPLV, YAGFLPV, YAGFLVP,PYAFLVG, PVLFYAG, A(2)PXA(3), and A(2)XPA(3) (where X = C, D, F, G, L, V, and Y, respectively). The resultshave shown that b (7) ions undergo head-to-tailcyclization and form a macrocyclic structure. Under the collision-induceddissociation (CID) condition, it generates nondirect sequence ionsregardless of the position of the proline and the neighboring aminoacid residues. This study highlights the unusual and unique fragmentationbehavior of proline-containing heptapeptides. Following the head-to-tailcyclization, the ring opens up and places the proline residue in theN-terminal position while forming a regular oxazolone form of b (2) ions for all peptide series. Then, the fragmentationreaction pathway is followed by the elimination of proline with itsC-terminal neighbor residue as an oxazolone (e.g., PXoxa) for all proline-containing peptide series.Article Citation - WoS: 1Citation - Scopus: 2A Molecularly Imprinted Polymer as Solid Phase Extraction Sorbent for Ketoprofen Determination in Water and Artificial Serum Prior To Hplc(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2022) Shahwan, Talal; Gürel Özyurt, Elif; Özyurt, Ömer; Ölçer, Yekta Arya; Eroğlu, Ahmet Emin; Boyacı, EzelKetoprofen (KET) is an active pharmaceutical compound that has pain relieving and antipyretic effects. Its determination in body fluids and environmental waters is important due to widespread use of the compound. In this study, a selective and reliable method has been developed for the determination of ketoprofen in water and artificial serum using molecularly imprinted polymers (MIPs) as a solid phase extraction sorbent prior to HPLC-DAD detection. The MIP was synthesized by copolymerization of methacrylic acid (MAA) and trimethylpropane trimethacrylate (TRIM) in the presence of ketoprofen as the template. For the sake of comparison, nonimprinted polymer (NIP) was also synthesized under the same experimental conditions without the addition of ketoprofen under the same experimental conditions. Critical extraction parameters such as sample pH, shaking time and sorbent amount were optimized and adjusted to 8.0, 24 h, and 10.0 mg, respectively, for a sample volume of 10.0 mL. MIP showed higher selectivity than NIP towards ketoprofen in an artificial matrix containing another pain relieving drug, ibuprofen, and a cardiovascular drug, metoprolol. The proposed method was successfully applied for the detection of ketoprofen in spiked drinking water, tap water, and artificial serum samples, and showed satisfactory results with respective recoveries of 96.8 % (± 0.8), 93.7% (± 0.6), 62.2% (± 0.6), and 69.9% (± 0.6).Article Citation - WoS: 8Citation - Scopus: 7The Use of Mussel Shell as a Bio-Additive for Poly(lactic Acid) Based Green Composites(Lviv Polytechnic National University, 2021) Lap, Metehan Oğulcan; Kanbur, Yasin; Tayfun, ÜmitMussel shell is one of the most hazardous aquaculture wastes and its powder was used as an additive for bio-degradable poly (lactic acid) in this current study. Bio-composites were fabricated via conventional melt mixing technique followed by an injection moulding process. The effects of mussel shell powder inclusion on mechanical, melt-flow, water uptake and morphological performance of poly (lactic acid)-based green composites were reported.Article Citation - WoS: 6Citation - Scopus: 5Charmm Force Field Generation for a Cationic Thiophene Oligomer With Fftk(Springer, 2021) Kıbrıs, Erman; Nalıncı Barbak, Nehir; Elmacı Irmak, NuranIn the present work, CHARMM force field parameters are generated for a cationic oligomer of N, N, N-trimethyl-3-(4-methylthiophen-3-yl) oxy) propan-1-aminium) which has the potential for sensing biological molecules such as nucleic acids, nucleobases. We have used ffTK (force field tool kit) to obtain potential parameters. MD simulations are performed for 20-mer and its complexes with AMP and ATP. The simulation results are analyzed to see the number of phosphates in adenosine nucleotides effects on the structure of the backbone of oligomer. The UV-VIS calculations for the conformers which possess the most probable radius of gyration are carried out and compared to the experimental ones to validate the generated force field. Recent studies have shown that, biologically important anions (ATP, AMP, vb.) change the spectroscopic properties of cationic polythiophenes (CPT) in the solutions. This work aims to generate CHARMM compatible force field parameters for a CPT to explain experimental studies. The type of interactions will be investigated deeply to lead new biosensor studies by examining the formation and the structure of complexes that consist of a oligothiophene and biological molecules, ATP, AMP by molecular dynamic simulations.Letter Prof. Dr. O. Yavuz Ataman(TÜBİTAK, 2021) Eroğlu, Ahmet EminProf. Dr. O. Yavuz Ataman passed away on August 15, 2020, in Ankara. He was an academic as well as a social figure throughout his life. He had remarkable achievements in academy as a researcher, an educator, and an administrator. He was known for his unique approaches to the events in all aspects of life. With his beloved character, he was really special. With Prof. Ataman's passing away, the chemistry and especially analytical chemistry community have lost a very special member.Article Citation - WoS: 7Citation - Scopus: 8Investigation of Oxygen Evolution Reaction Performance of Silver Doped Ba0.5sr0.5co0.8fe0.2o3-Delta Perovskite Structure(Springer, 2020) Göl, Emre Yusuf; Aytekin, Ahmet; Özkahraman, Ecem Ezgi; Karabudak, EnginStudies on novel electrochemical catalyst synthesis for efficient oxygen evolution reaction (OER) attract the attention of researchers. In general, changing of synthesis method and the doping metal affect the electrochemical activities of BSCF. In this work, silver doped Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF-Ag) perovskite structure is shown to be a better electrocatalyst for oxygen evolution reaction (OER) due to its lower overpotential and extended durability. BSCF structure was synthesized by the EDTA-citric acid method. Appropriate amount of Ba(NO3)(2) and EDTA were dissolved 0.1 M NH4OH solution. Nitrate salts of other metals were dissolved in distilled water, then mixed with prepared Ba(NO3)(2) solution. The mixture was stirred at 70 degrees C until gelation occurred. The gelled samples obtained were baked in a drying oven at 250 degrees C for 24 h before being calcined at 1000 degrees C for 12 h. To achieve a current density of 10 mA cm(-2), BSCF-Ag has required an overpotential of 0.36 V, which is very low compared to BSCF. To determine the stability of BSCF-Ag, continuous chronopotentiometry tests were carried out for 5 h and at a constant current density of 10 mA cm(-2). BSCF-Ag was characterized by XRD, SEM, and XPS.Article Citation - WoS: 37Citation - Scopus: 41Determination of Olive Oil Adulteration With Vegetable Oils by Near Infrared Spectroscopy Coupled With Multivariate Calibration(SAGE Publications, 2010) Öztürk, Betül; Yalçın, Ayşegül; Özdemir, DurmuşThere has been growing public awareness about the health benefits of olive oil throughout the world in recent years, resulting in a significant increase in its consumption as part of the daily diet This demand has attracted fraudulent attempts to market olive oil which has been adulterated with cheaper oils. This study focuses on the near infrared (NIR) spectroscopic determination of adulteration of olive oil by vegetable oils using multivariate calibration. The binary, ternary and quaternary mixtures of olive, soybean, cotton, corn, canola and sunflower oils were prepared using a random design. The absorbance spectra of these synthetic samples were measured by a near infrared (NIR) spectrometer. A genetic algorithm-based variable selection algorithm, coupled with an inverse least squares multivariate calibration method (GILS) was used to build calibration models for possible adulterants and olive oil in the adulterated mixtures The correlation coefficients of actual versus predicted concentrations resulting from multivariate calibration models for the different oils were between 0 90 and 0.99 The results demonstrated that NIR spectroscopy in conjunction with the GILS method makes it possible to determine the adulteration of olive oils regardless of adulterant vegetable oils over a wide range of concentrations.Article Citation - WoS: 2Citation - Scopus: 2Transition-Metal Direct C-H Arylation of Thiophene in Aqueous Media Via Potassium Peroxymonosulfate(John Wiley and Sons Inc., 2019) Özenler, Sezer; Kaya, Hakan; Elmacı, Nuran; Yıldız, Ümit HakanThis study covers the use of potassium peroxymonosulfate (PPS) which, is a mild and inexpensive catalyst, for direct coupling of C-H/C-H for water soluble thiophene. The 3-(4-methyl-3 '- thienyloxy)propyltriethylammonium bromide (M1) has been selected as model monomer that reacted PPS in 2.0, 0.20 and 0.020 monomer to PPS ratio. The reaction has been monitored via NMR spectroscopy revealing the monomer consumption and formation of dimers to tetramers as well as completion of reaction within 15 minutes. Resultant product is easily collected without tedious work up steps. The computational calculation has optimized the regularity of the coupling as head to tail, tail to tail, head to tail (HT-TT-HT) for tetramer. The regularity of tetramer which is further satisfied via NMR analysis showing emergence of new peaks at 3.56 and 4.48. The shifts in the UV maximum of reactive species have been monitored by absorbance spectroscopy showing time dependent red shift corresponds to growing from monomer to tetramers. The reaction has self-stopped due to low solubility of moderate condensates (higher than trimer), however further experiments have performed in water-organic mixtures showed great promises to obtain higher condensates.Editorial Citation - WoS: 8Citation - Scopus: 9Kras(g12c) Inhibitors on the Horizon(Future Science, 2019) Çağır, Ali; Azmi, Asfar S.RAS proteins (the four isoforms KRAS4A, KRAS4B, NRAS and HRAS encoded by three genes KRAS, NRAS and HRAS) act as molecular switches that when activated drive several key cellular processes such as cell growth, proliferation and survival [1]. In normal cells, RAS activity is under tight control by the precise activation (binding to GTP) and inactivation (GTP hydrolysis to GDP) [1]. As with other critical proteins, it is not at all surprising to note that the gene encoding the RAS protein isoforms is found mutated or altered in a significant proportion of tumors [2]. Mutant RAS loses its ability to hydrolyze GTP and remains in a permanently activated state (bound to GTP) leading to uncontrolled growth.Article Citation - WoS: 6Citation - Scopus: 6Palladium-Catalysed Reactions of Conjugated Enyne Oxiranes With Organoborons: a Diastereoselective Method of the Synthesis of 2,4,5-Trienol Derivatives(Elsevier, 2017) Ziyanak, Fırat; Kuş, Melih; Alkan Karadeniz, Leman; Artok, LeventA palladium-catalysed reaction of conjugated enyne oxiranes with organoboron reagents is described. This method allows aryl-substituted vinylallenes containing a hydroxyl group on the allylic position to be synthesized, with good diastereomeric ratios, under mild conditions.