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Identifier 000422960
Title A. Στερεοεκλεκτικές αναγωγές α-κυανοαιθυλο-β-κετο εστέρων καταλυόμενες από NADPH-εξαρτώμενες κετορεδουκτάσες Β. Μελέτη δραστικότητας, ειδικότητας της νέας θερμοανθεκτικής εστεράσης EstDZ2
Alternative Title A. Stereoselective reductions of α-cyanoethyl-β- keto esters catalyzed by isolated NADPH-dependent ketoreductases B. Activity and specificity studies of the new thermostable esterase EstDZ2
Author Μυρτολλάρη, Καμέλα Λ.
Thesis advisor Σμόνου, Ιουλία
Reviewer Παυλίδης, Ιωάννης
Στρατάκης, Μανώλης
Abstract Biocatalysis has received increased attention the last decades, revealing the significance of enzymes in organic synthesis. Enzymes have become an attractive choice in organic chemistry as renewable and natural biological catalysts and contribute to the simplification and ease of a synthetic process. What is more, by using enzymes, the use of toxic or harmful reagents in a big scale can be avoided. Our research group is working in the field of Biocatalysis focusing in the stereoselective synthesis of optically active compounds which are particularly important as chiral intermediates in pharmaceuticals. Recently in our group the chemoenzymatic synthesis of β-hydroxy-α-cyanoethyl-esters and their cyclization to γ-lactams was described. Lactams are compounds that have attracted great research interest as high added value intermediates due to their biological activity. Given the importance of amide rings in pharmaceutical compounds, we extended our previous study to the synthesis of designed optically active β-hydroxy-α-cyanoethyl esters for the stereoselective synthesis of δ-lactams. In the first chapter of this postgraduate dissertation the synthesis of α-cyanoethyl-β-ketoesters is described and their enzymatic reduction was studied using a series of NADPH dependent ketoreductases. Stereoselectivity of these reactions was also determined. The second chapter focuses to the class of hydrolytic enzymes. In particular, the hydrolytic activity of the new esterase EstDZ2 was studied for the first time. The new esterase is thermostable, with a half-life of more than six hours and exhibits excellent stability at high concentrations of organic solvents. Initially, the ability of the new enzyme to catalyze the hydrolysis of a series of aryl p-substituted esters of butyric acid was studied. The reaction conditions were optimized for the hydrolytic reaction. In all cases, a satisfactory conversion of the aryl ester substrate to the corresponding alcohol was achieved, regardless of the type or the position of the substituent on the aromatic ring. Also, the ability of EstDZ2 to hydrolyze esters from secondary alcohols was studied. Finally, the ability of EstDZ2 to catalyze the transesterification of secondary alcohols was investigated, as well as the factors which affect the stereoselectivity and catalytic ability of the new enzyme.
Language Greek
Subject Biocatalysis
Hydrolysis
Thermostable esterase
Transesterification
Βιοκατάλυση
Θερμοσταθερή εστεράση
Μετεστεροποίηση
Υδρόλυση
Issue date 2019-07-24
Collection   School/Department--School of Sciences and Engineering--Department of Chemistry--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/e/f/a/metadata-dlib-1559903229-269717-10499.tkl Bookmark and Share
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