Browsing by Author "Servili, B."

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Citation - Scopus: 0
Biocontrol Potential of Vibrio Maritimus Chitinase: Heterologous Expression and Insecticidal Activity Against Acanthoscelides Obtectus
(Elsevier B.V., 2025) Dikbaş, N.; Tülek, A.; Uçar, S.; Alim,; Servili, B.; Paçal, N.; Ercisli, S.
In this study, the chitinase gene from the marine bacterium Vibrio maritimus was heterologously expressed in Escherichia coli, purified via affinity chromatography and tested for its insecticidal activity against the storage pest Acanthoscelides obtectus. The recombinant VmChiA protein exhibited a molecular mass of ∼60 kDa, with optimum activity observed at pH 6.0 and 40 °C. Enzyme kinetic analysis revealed a Km value of 0.042 mM, Vmax of 17.48 μmol min−1, kcat of 1.75 min−1 and catalytic efficiency of 41.61 mM−1 min−1, respectively. Furthermore, a dose of 40 U mL−1 of recombinant VmChiA showed similar efficacy to malathion insecticide against A. obtectus, with 100 % mortality in both treatments. LC50 and LC90 values of VmChiA were 13.95 U mL−1 and 27.66 U mL−1, respectively. Furthermore, the three-dimensional structure of the catalytic site of VmChiA was modeled. Molecular dynamics simulation technique was used to explore and analyze the dynamics and interactions. A salt bridge (GLU274-ARG296) in the α + β domain was observed as a critical feature facilitating substrate (GlcNAc)2 binding and enzymatic activity. These findings demonstrate that recombinant VmChiA possesses potent insecticidal properties, highlighting its potential as a bio-based, eco-friendly alternative for managing significant agricultural pests. © 2025 Elsevier B.V.
Citation - Scopus: 0
Integrating Computational and Experimental Insights Into Osmolyte-Driven Activation of Geobacillus Kaustophilus L-Asparaginase for Acrylamide Mitigation
(Elsevier B.V., 2025) Özdemir, F.İ.; Servili, B.; Demirtaş, Ö.; Şükür, G.; Tülek, A.; Yildirim, D.
Osmolytes play a critical role in enhancing the stability and activity of enzymes for industrial applications. This study systematically investigated the effects of various osmolytes on the activity, optimal pH, temperature, stability, metal ion effects, storage, and acrylamide mitigation performance of L-asparaginase from the thermophilic Geobacillus kaustophilus (GkASNase). The experimental findings were further supported by computationally integrated tools such as homology modeling, docking, and molecular dynamics (MD) simulations. Among the selected osmolytes (maltose, sorbitol, trehalose, glycine, and sucrose), GkASNase showed the highest stability during 30 days of storage in the presence of maltose and arginine. Maltose increased GkASNase activity approximately 2-fold at 37 °C and 55 °C. In the presence of osmolytes, the Km values of GkASNase decreased and the Vmax values increased compared to controls at 37 °C and 55 °C. In the presence of osmolytes, the acrylamide mitigation performance of GkASNase increased by 1.7-fold in a 15 min reaction. The computational analysis indicates that L-asparagine as substrate enhances protein compactness and stability, while arginine as osmolyte increases flexibility and optimizes water distribution around the enzyme. These findings provide novel insights into enzyme stabilization that have implications for therapeutic and biotechnological applications. © 2025 Elsevier B.V.