WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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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: 16Citation - Scopus: 15Gene Cloning, Heterologous Expression, and Partial Characterization of a Novel Cold-Adapted Subfamily I.3 Lipase From Pseudomonas Fluorescence Ke38(Nature Publishing Group, 2020) Karakaş, Fulya; Arslanoğlu, AlperA novel cold-active true lipase from Pseudomonas sp. KE38 was cloned, sequencing and expressed in E. coli by degenerate PCR and genome walking technique. The open reading frame of the cloned gene encoded a polypeptide chain of 617 amino acids with a confirmed molecular weight of 64 kD. Phylogenetic analysis of the deduced amino acid sequence of the lipase indicated that it had high similarity with lipases of subfamily ?.3 of bacterial lipases. Recombinant lipase was purified in denatured form as inclusion bodies, which were then renatured by urea followed by dialysis. Lipase activity was determined titrimetrically using olive oil as substrate. The enzyme showed optimal activity at 25 °C, pH 8.5 and was highly stable in the presence of various metal ions and organic solvents. Low optimal temperature and high activity in the presence of methanol and ethanol make this lipase a potential candidate for transesterification reactions and biodiesel production. © 2020, The Author(s).Article Citation - WoS: 1Citation - Scopus: 1Human Immunodeficiency Virus Type-1 Tat Protein Induces Secretory Leukocyte Protease Inhibitor Expression in African Green Monkey but Not Human Cells(Springer, 2020) Özdemir, Selçuk; Şengez, Burcu; Arslanoğlu, AlperAfrican monkeys are resistant to HIV-1 infection due to intrinsic restriction mechanisms found in their cells. However, although they can be infected by monkey-adapted modified HIV-1 particles that are designed to overcome known restriction factors, virus numbers drop to undetectable levels in immunocompetent animals. These results indicate the possibility of the presence of yet unidentified factor(s) that restrict HIV-1 in old-world monkey (OWM) cells after integration of the viral genome into the host cell chromosome. In the light of these findings, we hypothesized that OWMs might have evolved resistance mechanism(s) against HIV-1 by switching specific gene(s) on in response to the synthesis of viral proteins in infected cells. In an attempt to mimic post-infection status, we expressed HIV-1 Tat gene in African green monkey cells and compared the whole proteome with normal cells and identified secretory leukocyte protease inhibitor (SLPI), a protein with known extracellular anti-HIV-1 activity, as an over-expressed protein in the presence of HIV-1 Tat protein by 2D-PAGE and mass spectrometry analysis. We also showed that overexpression of SLPI in the presence of HIV-1 Tat was specific to monkey cells. Our results also suggest that SLPI had a previously undiscovered intracellular anti-HIV activity in addition to its extracellular activity.Article Citation - WoS: 27Citation - Scopus: 36Purification and Biochemical Characterization of an Extracellular Lipase From Psychrotolerant Pseudomonas Fluorescens Ke38(TUBITAK, 2013) Adan Gökbulut, Aysun; Arslanoğlu, AlperAn extracellular lipase producing bacterium was isolated from a soil sample, and identified as a strain of Pseudomonas fluorescens by 16S rRNA gene sequencing. It was named Pseudomonas fluorescens KE38. KE38 showed psychrotolerant properties with an optimum growth temperature of 25 °C. The lipase enzyme secreted by KE38 was purified 41.13-fold with an overall yield of 54.99%, and a specific activity of 337.3 U/mg. The molecular mass of purified lipase was estimated to be approximately 43 kDa by SDS-PAGE. Although the lipase was active at a temperature range of 15-65 °C, it exhibited maximum activity at 45 °C, at pH 8.0. The enzyme exhibited high stability retaining 100% and 70% of its activity after an incubation period of 45 and 100 min at 45 °C and pH 8.0 respectively. It also showed a broad substrate specificity acting on p-nitrophenyl esters with C8-C18 acyl groups as substrates and was activated by Ca2+ and Ni2+ at 1 mM. While the enzyme retained its activity levels in the presence of a variety of organic solvents, DMSO and dimethylformamide enhanced this. High stability, broad substrate specificity and activity at cold temperatures in the presence of organic solvents, and metal ions make the extracellular lipase of KE38 a candidate for industrial applications.Article Citation - WoS: 125Citation - Scopus: 156Antimicrobial and Antioxidant Activity of Edible Zein Films Incorporated With Lysozyme, Albumin Proteins and Disodium Edta(Elsevier Ltd., 2007) Mecitoğlu Güçbilmez, Çiğdem; Yemenicioğlu, Ahmet; Arslanoğlu, AlperIn this study, partially purified lysozyme was incorporated into zein films in combination with chickpea albumin extract (CPAE), bovine serum albumin (BSA) and disodium EDTA. The zein films showed an inherent free radical scavenging activity. Incorporation of lysozyme did not contribute to soluble free radical scavenging activity of zein films. However, the incorporation of lysozyme in combination with CPAE increased the soluble and immobilized free radical scavenging activity of zein films 17% to 25% and almost 84%, respectively. The incorporation of CPAE also improved the distribution of partially purified lysozyme preparation in zein films and enabled the controlled release of lysozyme by reducing its release rate from zein films between 1.5- and 3.5-fold, depending on the concentration of incorporated CPAE. In contrast, the BSA incorporation made distribution of lysozyme more heterogeneous and it did not contribute to the free radical scavenging activity of films significantly. The combinational incorporation of partially purified lysozyme with disodium EDTA · 2H2O or CPAE and disodium EDTA · 2H2O gave zein films effective on Escherichia coli and Bacillus subtilis. This study clearly showed the benefits of using functional protein extracts to control lysozyme distribution and release rate and to improve antioxidant activity in zein films.Article Citation - WoS: 125Citation - Scopus: 147Incorporation of Partially Purified Hen Egg White Lysozyme Into Zein Films for Antimicrobial Food Packaging(Elsevier Ltd., 2006) Mecitoğlu, Çiğdem; Yemenicioğlu, Ahmet; Arslanoğlu, Alper; Elmacı, Zehra Seda; Korel, Figen; Çetin, Ali EmrahLysozyme, partially purified from hen egg white by precipitation of non-enzyme protein with ethanol and lyophilized after dialysis, was incorporated into zein films. The recovery and specific activity of the enzyme after partial purification varied between 45% and 72% and 2173 and 3448 U/mg, whereas the activity of the lyophilized enzyme varied between 2900 and 3351 U/mg. The partially purified enzyme was very stable and lost almost no activity in lyophilized form or in zein films stored at -18 and 4°C for up to 8 and 4 months, respectively. During partial purification and in zein film preparation, ethanol treatment caused 123-137% and 132-315% activation of the enzyme, respectively. In zein films incorporated with 187-1318 U/cm2 (63-455 μg/cm2) lysozyme, the release rates at 4°C, changed between 7 and 29 U/cm2/min, increased at high lysozyme concentrations. Zein films incorporated with partially purified lysozyme showed antimicrobial effect on Bacillus subtilis and Lactobacillus plantarum. By the addition of disodium EDTA, the films also became effective on Escherichia coli. The results of this study showed that the partially purified lysozyme may be used in antimicrobial packaging to increase food safety.Article Citation - WoS: 39Citation - Scopus: 49Production of Antimicrobial Films by Incorporation of Partially Purified Lysozyme Into Biodegradable Films of Crude Exopolysaccharides Obtained From Aureobasidium Pullulans Fermentation(University of Zagreb, 2005) Kandemir, Nilay; Yemenicioğlu, Ahmet; Mecitoğlu, Çiğdem; Elmacı, Zehra Seda; Arslanoğlu, Alper; Göksungur, Mehmet Yekta; Baysal, TanerAntimicrobial films were produced by incorporating partially purified lysozyme into films of crude exopolysaccharides (59% pullulan) obtained from Aureobasidium pullulans fermentation. After film making, the films containing lysozyme at 100, 260, 520 and 780 μg/cm2 showed 23 to 70% of their expected enzyme activities. The highest recovery of enzyme activity (65-70%) after the film making was obtained in films prepared by incorporating lysozyme at 260 μg/cm2 (1409 U/cm2). The incorporation of disodium EDTA·2H2O and sucrose did not affect the initial lysozyme activity of the films significantly. With or without the presence of disodium EDTA·2H2O at 52 or 520 μg/cm2, lysozyme activity showed sufficient stability in the films during 21 days of cold storage. However, the presence of sucrose at 10 mg/cm2 in the films caused the destabilization of part of enzyme activity (almost 35%) at the end of storage. The combinational incorporation of lysozyme at 780 μg/cm 2 (4227 U/cm2) and disodium EDTA·2H2O at 520 μg/cm2 gave antimicrobial films effective on Escherichia coli. However, in the studied lysozyme concentration range the films did not show any antimicrobial activity against Lactobacillus plantarum. This study clearly showed that the partially purified lysozyme and crude exopolysaccharides from Aureobasidium pullulans may be used to obtain antimicrobial films to increase the safety of foods.