PhD student
Group of Prof. Uwe T. Bornscheuer
Department of Biotechnology & Enzyme Catalysis, University of Greifswald
Contact email: askin.aslanuezel@uni-greifswald.de
ES-Cat start date: 1st April 2017

Background:
I received my BSc degree in Chemistry from Yıldız Technical University (Turkey) and my MSc degree in Molecular Biology, Genetic & Biotechnology from Istanbul Technical University (Turkey). My undergraduate studies dealt with the immobilization of pullulanase and investigation of some properties of the immobilized and free enzyme. In my master’s degree, I had the opportunity to visit the Manchester Institute of Biotechnology (UK) as a guest researcher under the supervision of Prof. Nicholas J. Turner. The goal of my work was to use site-directed mutagenesis to generate variants of Geobacillus stearothermophilus L-lactate dehydrogenase for production of industrially important chiral 𝛼-hydroxy acids. I also briefly worked with xylanase and several formate dehydrogenases under the supervision of Dr Ossi Turunen at Aalto University (Finland). My goal was to obtain a novel NADH-dependent formate dehydrogenase to reduce atmospheric CO2 and to improve its catalytic properties.

Training and Transferable Skills:

  • Biochemistry (recombinant protein expression, purification and characterization)
  • Enzymology and Biocatalysis (kinetics, screening, activity assay for xylanases, dehydrogenases etc.)
  • Molecular biology (PCR, Site-directed mutagenesis, cloning, sequencing)Analytical techniques

Research Projects:
Catalytic promiscuity is an intriguing deviation from the classical concept of enzyme function. Enzymes are usually known for their exquisite specificities, yet several enzymes can catalyze alternative reactions, distinct from the reaction for which they had been selected. Catalytic promiscuity is important in enzyme engineering as it provides valuable starting points for the directed evolution of novel enzyme activities. The aim of my project is to study the interconversion of epoxide hydrolase and haloalkane dehalogenase activities. This will be done by reconstructing ancestral enzymes, as it is hypothesized that ancestral enzymes should be less specialized and more promiscuous. To identify residues important in determining substrate specificity and to reconstruct the sequence of the last universal common ancestor (LUCA), we will make use of multiple sequence alignment, phylogenetic analyses, and the 3DM database. Results of this study will illuminate the evolutionary path from ancestral variants to extant epoxide hydrolases and haloalkane dehalogenases.

Publications:

Aslan A.S., Valjakka J., Ruupunen J., Yildirim D., Turner N. J., Turunen O., Binay B., 2017. Chaetomium thermophilum formate dehydrogenase has high activity in the reduction of hydrogen carbonate to formate. Protein Eng. Des. Select., 30, 47-55.

Yu T., Anbarasan S., Wang Y., Telli K., Aslan A.S., Su Z., Zhou Y., Zhang L., Iivonen P., Havukainen S., Mentunen T., Hummel M., Sixta H., Binay B., Turunen O., Xiong H., 2016. Hyperthermostable Thermotoga maritima xylanase XYN10B shows high activity at high temperatures in the presence of biomass-dissolving hydrophilic ionic liquids. Extremophiles, 20, 515-24.

Aslan A.S., Birmingham W.B., Karagüler N.G., Turner N.J., Binay B., 2016. Semi- Rational Design of Geobacillus stearothermophilus L-Lactate Dehydrogenase to Access Various Chiral α- Hydroxy Acids. Appl. Biochem. Biotechnol., 179, 474-84.