Yazar "Unal, Mehmet Altay" seçeneğine göre listele

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    Electrochemical detection of lactate produced by foodborne presumptive lactic acid bacteria
    (Soc Bioscience Bioengineering Japan, 2023) Ozoglu, Ozum; Uzunoglu, Aytekin; Unal, Mehmet Altay; Gumustas, Mehmet; Ozkan, Sibel Aysil; Korukluoglu, Mihriban; Altuntas, Evrim Gunes
    The detection of lactate is an important indicator of the freshness, stability, and storage stability of products as well as the degree of fermentation in the food industry. In addition, it can be used as a diagnostic tool in patients' healthcare since it is known that the lactate level in blood increases in some pathological conditions. Thus, the determination of lactate level plays an important role in not only the food industry but also in health fields. As a result, biosensor technologies, which are quick, cheap, and easy to use, have become important for lactate detection. In the current study, amperometric lactate biosensors based on lactate oxidase immobilization (with Nafion 5% wt) were designed and the limit of detection, linear range, and sensitivity values were determined to be 31 mu M, 50-350 mu M, and 0.04 mu A mu M-1 cm-2, respectively. Then, it was used for the measurement of lactic acid that produced by six different and morphologically identified presumptive lactic acid bacteria (LAB) which are isolated from different naturally fermented cheese samples. The biosensors were then used to successfully perform lactate measurements within 3 min for each sample, even though a few of them were out of the limit of detection. Thus, electrochemical biosensors should be used as an alternative and quick solutions for the measurement of lactate metabolites rather than the traditional methods which require long working hours. This is the first study to use a biosensor to measure lactate produced by foodborne LAB in a real sample. (c) 2023, The Society for Biotechnology, Japan. All rights reserved.
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    Functional analyses of three different mutations in the AVP-NPII gene causing familial neurohypophyseal diabetes insipidus
    (Springer, 2021) Turkmen, Merve Ozcan; Karaduman, Tugce; Tuncdemir, Beril Erdem; Unal, Mehmet Altay; Mergen, Hatice
    Purpose Familial neurohypophyseal diabetes insipidus (FNDI), a rare disorder, which is clinically characterized by polyuria and polydipsia, results from mutations in the arginine vasopressin-neurophysin II (AVP-NPII) gene. The aim of this study was to perform functional analyses of three different mutations (p.G45C, 207_209delGGC, and p.G88V) defined in the AVP-NPII gene of patients diagnosed with FNDI, which are not included in the literature. Methods For functional analysis studies, the relevant mutations were created using PCR-based site-directed mutagenesis and restriction fragment replacement strategy and expressed in Neuro2A cells. AVP secretion into the cell culture medium was determined by radioimmunoassay (RIA) analysis. Fluorescence imaging studies were conducted to determine the differences in the intracellular trafficking of wild-type (WT) and mutant AVP-NPII precursors. Molecular dynamics (MD) simulations were performed to determine the changing of the conformational properties of domains for both WT and 207-209delGGC mutant structures and dynamics behavior of residues. Results Reduced levels of AVP in the supernatant culture medium of p.G45C and p.G88V transfected cells compared to 207_209delGGC and WT cells were found. Fluorescence imaging studies showed that a substantial portion of the mutant p.G45C and p.G88V AVP-NPII precursors appeared to be located in the endoplasmic reticulum (ER), whereas 207_209delGGC and WT AVP-NPII precursors were distributed throughout the cytoplasm. Conclusions The mutations p.G45C and p.G88V cause a failure in the intracellular trafficking of mutant AVP-NPII precursors. However, 207_209delGGC mutation does not result in impaired cellular trafficking, probably due to not having any significant effect in processes such as the proper folding, gain of three-dimensional structure, or processing. These results will provide valuable information for understanding the influence of mutations on the function of the AVP precursor hormone and cellular trafficking. Therefore, this study will contribute to elucidate the mechanisms of the molecular pathology of AVP-NPII mutations.