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Komarova N.V.,RAS A.N. Bach Institute of Biochemistry | Golubev I.V.,Moscow State University | Khoronenkova S.V.,Innovations and High Technologies MSU Ltd. | Tishkov V.I.,RAS A.N. Bach Institute of Biochemistry
Russian Chemical Bulletin

d-Amino acid oxidase from the yeast Trigonopsis variabilis (TvDAAO) is widely used in fine organic synthesis, including the preparation of unnatural l-amino acids and α-keto acids. The analysis of the three-dimensional structure of TvDAAO was carried out with the aim of producing the enzyme specific to d-amino acids with bulky side chains. The analysis revealed the residue Phe54 at the entrance to the active site, which controls the substrate access to this site. The residue Phe54 was replaced by residues Ala, Ser, and Tyr. The cultivation of recombinant E. coli strains expressing TvDAAO mutants showed that the mutein with the Phe54Ala substitution had very low stability. Thus, the inactivation of the enzyme occured within 10 min after the cell disruption. The Phe54Ser TvDAAO and Phe54Tyr TvDAAO mutants were obtained as homogeneous preparations, and their thermal stability and catalytic properties were investigated. The introduction of Phe54Ser and Phe54Tyr substitutions resulted in additional stabilization of the protein macromolecule compared to the wild-type TvDAAO. Thus, the half-inactivation time for the mutant enzymes at 54 C increased by a factor of 1.5 and 2, respectively. As in the case of wild-type TvDAAO, the thermal inactivation of the muteins proceeds via a two-step dissociative mechanism. The introduction of mutations led to a strong change in the substrate specificity profile. The mutants have no activity toward a series of d-amino acids (Phe54Ser TvDAAO toward d-Ala, d-Ser, d-Val, and d-Thr; Phe54Tyr TvDAAO toward d-Ser, d-Tyr, d-Thr, and d-Lys). The catalytic efficiency (the k cat/K M ratio) of the Phe54Ser TvDAAO mutant toward d-amino acids with bulky side chains (d-Lys, d-Asn, d-Phe, d-Tyr, d-Trp, and d-Leu) increased from 2.4 to 7.3 times. © 2012 Springer Science+Business Media New York. Source

Zakhariants A.A.,Moscow State University | Poloznikov A.A.,Burke Medical Research Institute | Poloznikov A.A.,Innovations and High Technologies MSU Ltd. | Smirnova N.A.,Burke Medical Research Institute | And 2 more authors.
Russian Chemical Bulletin

The flavin adenine dinucleotide-containing domain of the protein MICAL (molecule interacting with CasL) is a monooxygenase. This protein plays an important role in the regulation of axonal guidance. However, the mechanism of this process has been unknown until recently. Only two years ago, F-actin was found to be the physiological substrate. The oxidation of methionine residues of this substrate is catalyzed by MICAL, resulting in the depolymerization of actin. A year ago it was shown that methionine sulfoxide reductase (MSR) catalyzes the reverse reaction of reduction of oxidized actin methionines. Therefore, this couple of proteins is currently a target for manipulation of the ability of neurons to regenerate their axons. The present study deals with different approaches to the regulation of the activity of MICAL and MSR and the design of inhibitors of the former enzyme. © 2014 Springer Science+Business Media New York. Source

Poloznikov A.A.,Innovations and High Technologies MSU Ltd. | Zakharova G.S.,Russian Academy of Sciences | Chubar T.A.,Russian Academy of Sciences | Hushpulian D.M.,Moscow State University | And 2 more authors.
Moscow University Chemistry Bulletin

Tobacco anionic peroxidase (TOP) mutant Ile37Met was produced by site-directed mutagenesis to mimic soybean peroxidase (SBP), in which Met37 is responsible for increased thermal stability. TOP Ile37Met was expressed in E. coli BL21(DE3) CodonPlus in the form of bodies. The expression level of the constructed enzyme was approximately 40% of the total E. coli protein. The enzyme was reactivated into an active and soluble form via a refolding procedure that was earlier developed for wild-type TOP. The substrate specificity, catalytic activity, and thermal stability of TOP Ile37Met were investigated. It was shown that the introduction of the Ile37Met mutation does not increases the stability of the enzyme; on the contrary, it leads to a reduction in the catalytic properties of the enzyme. © 2014 Allerton Press, Inc. Source

Komarova N.V.,Innovations and High Technologies MSU Ltd. | Golubev I.V.,Moscow State University | Khoronenkova S.V.,Moscow State University | Chubar T.A.,RAS A.N. Bach Institute of Biochemistry | Tishkov V.I.,RAS A.N. Bach Institute of Biochemistry
Biochemistry (Moscow)

Natural D-amino acid oxidases (DAAO) are not suitable for selective determination of D-amino acids due to their broad substrate specificity profiles. Analysis of the 3D-structure of the DAAO enzyme from the yeast Trigonopsis vari- abilis (TvDAAO) revealed the Phe258 residue located at the surface of the protein globule to be in the entrance to the active site. The Phe258 residue was mutated to Ala, Ser, and Tyr residues. The mutant TvDAAOs with amino acid substitutions Phe258Ala, Phe258Ser, and Phe258Tyr were purified to homogeneity and their thermal stability and substrate specificity were studied. These substitutions resulted in either slight stabilization (Phe258Tyr) or destabilization (Phe258Ser) of the enzyme. The change in half-inactivation periods was less than twofold. However, these substitutions caused dramatic changes in substrate specificity. Increasing the side chain size with the Phe258Tyr substitution decreased the kinetic param- eters with all the D-amino acids studied. For the two other substitutions, the substrate specificity profiles narrowed. The cat- alytic efficiency increased only for D-Tyr, D-Phe, and D-Leu, and for all other D-amino acids this parameter dramatical- ly decreased. The improvement of catalytic efficiency with D-Tyr, D-Phe, and D-Leu for TvDAAO Phe258Ala was 3.66-, 11.7-, and 1.5-fold, and for TvDAAO Phe258Ser it was 1.7-, 4.75-, and 6.61-fold, respectively. © Pleiades Publishing, Ltd., 2012. Source

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