Biochemistry and Biochemical Engineering

 

 

Head - Professor Florin-Dan IRIMIE                                   irimie@chem.ubbcluj.ro

 

Associate professor Csaba PAIZS                                    paizs@chem.ubbcluj.ro

 

Assistant professor Monica-Ioana TOSA              mtosa@chem.ubbcluj.ro

 

Assistant Paula-Veronica MOLDOVAN                            mpaula@chem.ubbcluj.ro

 

Associate professor Radu SILAGHI-DUMITRESCU        rsilaghi@chem.ubbcluj.ro

 

Technical staff: Mrs. Ibolya VARGA                                    ivarga@chem.ubbcluj.ro

 

Technical staff: Mr. Ioan BODEA

 

Our research is in the areas of fine organic synthesis, selective enzymatic and cellular bioprocesses, separation processes, bioprocess engineering, experimental and computational bioinorganic chemistry, oxidative and nitrosative stress, blood substitutes.

 

Phenylalanine ammonia-lyase (PAL) is an important plant enzyme, as its product, (E)-cinnamic acid is the precursor of lignins, coumarins, and flavonoids. PAL and the related histidine ammonia-lyase (HAL) contain the unique superelectrophilic prosthetic group 5-methylene-3,5-dihydroimidazol-4-one (MIO). MIO has the unusual ability to form a transient bond with the aromatic ring of the substrate (phenylalanine or histidine), resulting in activation of its β-protons for abstraction by an active-site base; this proton abstraction leads to cleavage of the neighboring C-NH3 bond in the substrate, liberating ammonia. This mechanism, initiated by a Friedel–Crafts type attack, is illustrated below.

An interesting property of PAL is its ability to react with a large number of arylalanines, which makes it a useful enantiospecific biocatalyst. At a surprisingly high ammonia concentration (~6 M) both the PAL and HAL reactions can be run in the reverse direction, that is, the enantioselective addition of ammonia can be achieved on a preparative scale. Thus the pure l-enantiomers of various halogen-substituted phenylalanines (Cl, F), pyridyl and pyrimidyl alanines etc. have been prepared by the reverse PAL reaction. We have synthesized various acrylic acids, substituted with heterocyclic aromatic groups, and the corresponding amino acids both in the racemic and enantiomerically pure form. These compounds, illustrated below (series 7 and 9), were then shown to be either substrates or inhibitors of PAL (see below for binding modes of our compounds to the enzyme, as suggested by experiments).

 

 

Besides the practical utility in synthesis, such studies help us better understand substrate binding and the mechanism of this class of enzymes (e.g., Scheme below).

 

 

Currently, the lipase-catalyzed kinetic resolution of racemic compounds with various functionalities has become an important method for the preparation of enantiopure compounds. When the method is successful both enantiomers of a racemate at ca. 50% theoretical yields are simultaneously available for drug development. However, it can occur that the other enantiomer exerts a different, even harmful, physiological effect or shows lowered or no activity. Accordingly, there is a final bias towards the preparation of only one of the enantiomers, leaving behind the question about what to do with the undesired enantiomer of the kinetic resolution. To solve this problem, the principle of dynamic kinetic resolution ca be exploited, as shown by our work (Scheme below) where an efficient one-pot synthesis of optically active cyanohydrin esters in the presence of a basic resin and a lipase (Candida arctica lipase A, CAL-A).

 

Alongside lipases, we have also employed baker’s yeast as a selective reducing agent, as illustrated by the Scheme below:

 

Indeed, in certain instances, baker’s yeast can prove to be a more efficient reducing agent than traditional chemicals – as we have found in the series of reactions illustrated below.

 

 

 

            As can be seen above, we typically combine organic synthesis with enzymatic and whole-cell biotransformations, most often with the aim of obtaining/transforming drugs and enantio-pure products.

 

 

Publications:

 

Books:

Irimie Florin Dan, Elemente de Biochimie -I. Editura Erdelyi Hirado, Cluj-Napoca 1999.

Irimie Florin Dan, Paizs Csaba, Toşa Monica Biotransformări în sinteza organică. Aspecte Fundamentale. Editura Napoca Star, Cluj-Napoca 2006.

M1 . Moldovan Paula, Toşa Monica Ioana, Leţ Daniela, Majdik Cornelia, Paizs Csaba, Irimie Florin Dan Aplicaţii pentru laboratorul de biochimie Editura Napoca Star, Cluj Napoca 2006.

Radu Silaghi-Dumitrescu, Horseradish peroxidase – a versatile catalyst, 2006, Research Signpost, India

 

 

Articles:

  • Henrietta Endrédi, Ferenc Billes*, Monica Toşa, Cornelia Majdik, Florin Dan Irimie “Experimental and quantum chemical study on the vibrational spectroscpy of N-methylphenothiazines. Part 1.”, Spectrochimica Acta Part A: Mol. & Biomol. Spectroscopy, 2006, 63, 349-360
  • Anikó Takátsy , Judit Hodrea , Cornelia Majdik, Florin Dan Irimie , Ferenc Kilár:  Role of chemical structure in molecular recognition by transferrin, Journal of Molecular Recognition, 2006, 19, 270 – 274
  • Takatsy, A., Hodrea, J., Majdik, C., Irimie, F. D., Kilar, F: Role of chemical structure in molecular  recognition  followed by capillary electrophoresis. Journal of Chromatography A, 2005, 6,78-86
  • Katona, A., Toşa, M. I., Paizs, Cs., Rétey, J. (2006) Inhibition of Histidine Ammonia-Lyase by Heteroaryl-alanines and Acrylates. Chemistry and Biodiversity 3, 502-508.
  • Paizs, Cs., Katona, A., Rétey, J. (2006) Chemoenzymatic One-Pot Synthesis of Enantio-Pure l-Arylalanines From Arylaldehydes. European Journal of Organic Chemistry 1113-1116.
  • Paizs, Cs., Katona, A., Rétey, J. (2006) The Interaction of Heteroaryl-Acrylates and Alanines with Phenylalanine Ammonia-Lyase from Parsley. Chemistry, a European Journal 12, 2739-2744.
  • Iliescu, T., Maniu, D., Chiş, V., Irimie, F. D., Paizs, Cs., Toşa, M. (2004) NIR surface enhanced Raman spectroscopy and bands assignment by DFT calculations of non-natural b-amino acids. Chemical Physics 310, 189-199
  • Paizs, Cs., Tähtinen, P., Toşa, M. I., Majdik, C., Irimie, F. D., Kanerva, L. T. (2004) Biocatalytic enantioselective preparation of phenothiazine-based cyanohydrin acetates: kinetic and dynami kinetic resolution. Tetrahedron 60, 10533-10540.
  • Paizs, Cs., Toşa, M. I., Bódai, V., Szakács, Gy., Kmecz, I., Simándi, B., Majdik, C., Novák, L., Irimie F. D., Poppe L. (2003): Kinetic resolution of 1-(benzofuran-2-yl)ethanols by lipase-catalyzed enantiomer selective reactions. Tetrahedron: Asymmetry 14, 1943-1949.
  • Paizs, Cs., Tähtinen, P., Lundell, K., Poppe, L., Irimie, F. D., Kanerva, L. T. (2003): Preparation of novel phenylfuran-based cyanohydrin esters: lipase-catalysed kinetic and dynamic resolution. Tetrahedron: Asymmetry 14, 1895-1904.
  • Bolboaca, M., Iliescu, T., Paizs, Cs., Irimie, F. D., Kiefer, W. (2003): Raman, Infrared, and Surface-Enhaced Raman Spectroscopy in Combination with ab initio and density functional theory calculations on 10-isopropyl- 10H-phenothiazine-5-oxide. Journal of Physical Chemistry A 107, 1811-1818
  • Paizs, Cs., Toşa, M. I., Majdik, C., Moldovan, P., Novák, L., Kolonits, P., Marcovici, A., Irimie, F. D., Poppe, L. (2003): Optically active 1-(benzofuran-2-yl)ethanols and ethane-1,2-diols by enantiotopic selective bioreductions. Tetrahedron: Asymmetry 14, 1495-1501.
  • Paizs, Cs., Toşa, M. I., Majdik, C., Tähtinen, P., Irimie, F. D., Kanerva, L. T. (2003): Preparation of novel furylbenzothiazol–based cyanohydrin esters: Candida Antarctica lipase A – catalysed kinetic and dynamic resolution. Tetrahedron: Asymmetry 14, 619-627.
  • Paizs, Cs., Toşa, M. I., Majdik, C., Bodai, V., Novák, L., Irimie, F. D., Poppe, L. (2002): Chemo-enzymatic preparation of hydroxymethyl ketones. Journal of the Chemical Society, Perkin Transactions 1 21, 2000-2002.
  • Irimie, F. D., Paizs, Cs., Toşa, M. I., Majdik, C., Mişca, R., Silaghi-Dumitrescu, R. (2002): Bioorganic synthesis of some (5-(benzothiazole-2-yl)furan-2-yl)methanols in cell catalysis using Saccharomyces cerevisiae. Heterocyclic Communications 8, 489-492.
  • Iliescu, T., Irimie, F. D., Bolboaca, M., Paizs, Cs., Kiefer, W. (2002): Surface enhanced Raman  spectroscopy of 5-(4-fluoro-phenyl)-furan-2-carbaldehyde adsorbed on silver colloid. Vibrational Spectroscopy 29, 251-255.
  • Iliescu, T., Irimie, F. D., Bolboaca, M., Paizs, Cs., Kiefer, W. (2002): Vibrational spectroscopic investigations of 5-(4-fluoro-phenyl)-furan-2-carbaldehyde. Vibrational Spectroscopy 29, 235-239.
  • Cimpoiu, C., Hodişan, T., Toşa, M. I., Paizs, Cs., Majdik, C., Irimie F. D. (2002): Separation of N-alkyl- phenothiazin- sulfones by HPTLC using an optimum mobile phase. Journal of Pharmaceutical and Biomedical Analysis 28, 385-359.
  • Toşa, M. I., Paizs, Cs., Majdik, C., Novák, L., Kolonits P., Irimie, F., Poppe, L. (2002): Optically active 3-substituted-10-alkyl-10H-phenothiazine-5-oxides by enantiomer selective biotransformations. Tetrahedron: Asymmetry 13, 211-221.
  • Toşa, M. I., Paizs, Cs., Majdik, C., Moldovan, P., Novák, L., Kolonits, P., Szabó, É., Poppe, L., Irimie, F. D. (2002): Baker’s yeast mediated preparation of (10-alkyl-10H-phenothiazin-3-yl)methanols. Journal of Molecular Catalysis B, Enzymatic 17, 241-248.
  • Toşa, M. I., Paizs, Cs., Majdik, C., Poppe, L., Kolonits, P., Silberg I. A., Novák, L., Irimie, F. D. (2001): Selective oxidation methods for preparation of N-alkylphenothiazine sulfoxides and sulfones. Heterocyclic Communications 7 277-282.
  • Grosu, I., Balog, M., Paizs, Cs., Ple, G., Irimie, F. D., Mager, S., Podea, R. (2000):  Synthesis and stereochemistry of some new 1,3-dioxane derivatives obtained from 5-aryl-2-furaldehydes. Revue Roumaine de Chemie 45, 877-882.
  • Irimie, F. D., Afloroaiei, C., Toşa, M. I., Paizs, Cs. (1999): Bioreduction with baker’s yeast of π-deficient heterocyclic aldehydes. Heterocyclic Communication 5, 253-256.
  • Damian, G., Cozar, O., Miclăuş, V., Paizs, Cs., Znamirovschi, V., Chiş, V., David, L. (1998): ESR Study of the dynamics of adsorbed nitroxide radicals on porous surfaces in the dehydratation process. Colloids and Surfaces A 137, 1-6.

·        Irimie, F. D., Paizs, Cs., Toşa, M. I., Afloroaiei, C., Miclăuş, V. (1997): Baker’s yeast mediated reductions of some nitrodibenzofurans. Heterocyclic Communications 3, 549-553.

  • Pop, Al., Paizs, Cs., Toşa, C., Toşa, M. I., Miclăuş, V. (1997): Oxidarea metanolului la formaldehidă pe catalizatori oxidici de Mo-Fe. II Modelarea matematică şi analiza procesului. Revista de chimie 48, 616-620.
  • Toşa, C., Miclăuş, V., Toşa, M. I., Pop, Al., Paizs, Cs. (1997): Oxidarea metanolului la formaldehidă pe  catalizatori oxidici de Mo-Fe. I Modelul matematic al bilanţului de masă. Revista de chimie  48, 284-290.
  • Iliescu, T.; Irimie, F. D.; Baia, M.; Paizs, Cs.; Bratu, I. (2003): IR absorption, FT-Raman and SERS investigations together with DFT calculations on a furan-2-carbaldehyde derivative. Asian Chemistry Letters 7, 213-220.
  • Paizs Cs., Majdik C., Toşa M., Mişca R., Irimie F. D. (2001): Synthesis of some 2-(Benzothiazol-2-yl)-Furans Mediated by Saccharomyces Cerevisiae. Roumanian Biotechological Letters 6, 325-31.
  • Toşa M., Paizs Cs., Majdik C., Mişca R., Irimie F. D. (2001): Baker’s Yeast Mediated Enantioselective Reduction of Phenothiazine Based Prochiral Ketones. Roumanian Biotechological Letters 6, 305-13.
  • Toşa M., Paizs Cs., Majdik C., Moldovan P., Mişca R., Irimie F. D. (2001): Chemoselective Bioreduction of 5-Nitrophenyl-furan-2-carbaldehydes Mediated by Baker’s Yeast. Roumanian Biotechological Letters 6, 273-9.
  • Toşa M., Paizs Cs., Majdik C., Mişca R., Irimie F. D. (2001): Synthesis and Chemoselective Bioreduction of  Some 10-Alkyl-10H-Phenothiazine-3-carbaldehyde-5,5 dioxides Mediated by Saccharomyces cerevisiae. Roumanian Biotechological Letters  6, 147-54.
  • Irimie F. D., Toşa M., Paizs Cs., Majdik C., Moldovan P., Silberg I.A. (2000): Biocatalytic Synthesis of Some Novel (10-Alkyl-10H-phenothyazine-3-yl)methyl Acetates Mediated by Lipase B from Candida antarctica. Roumanian Biotechological Letters 5, 55-62.
  • Majdik C., Paizs Cs., Tosa M., Irimie F. D. (2000): Bioreduction of Nitrobenzenzofurans Mediated by Saccharomyces Cerevisiae. Roumanian Biotechological Letters 5, 17-22.
  • Toşa, M. I., Irimie, F. D., Toşa, C., Paizs, Cs. (1999): Osmotic dehydration of strawberries in 60% sugar solution. III. The behavior of characteristica flavour compounds in strawberries. Roumanian Biotechnological Letters 4, 313-318.
  • Toşa, M. I., Irimie, F. D., Paizs, Cs., Toşa, C. (1999): Osmotic dehydration of strawberries in 60% sugar solution. II. The Carbohydrates Content and Vitamin C Retention. Roumanian Biotechnological Letters 4, 247-250.
  • Toşa, M. I., Irimie, F. D., Paizs, Cs., Toşa, C., Miclăuş, V. (1999): Osmotic dehydration of strawberries in  60% sugar solution. I. The drying curves and volume change of fruit. Roumanian Biotechnological Letters 4, 145-149.
  • Irimie, F. D., Paizs, Cs., Joó, Fr., Silaghi-Dumitrescu, R., Toşa, M. I., Majdik, C. (1999): Bioorganic Reduction of some 5-phenyl-furyl carboxaldehydes mediated by baker’s yeast. Roumanian Biotechnological Letters 4, 71-74.
  • Irimie, F., Paizs, Cs., Joó, Fr., Silaghi-Dumitrescu, R., Toşa, M. I., and Majdik, C. (1998): Reductive biotransformation of some 5-phenyl-furyl carboxaldehydes. Progress in Catalysis 8, 70-73.
  • Damian, G., Cozar, O., Miclăuş, V., Paizs, Cs., Todică, M., Chiş, V. (1997): ESR Study of the   dynamics of adsorbed nitroxide in the slow-motional regime absorbed on hydrophobic and hydrophilic surfaces. Balkan Physics Letters 5, 289-293.
  • Miclăuş, V., Damian, G., Făgărăşan, V., Câmpan, G., Stamate, S., Paizs, Cs.  (1997): Spectroscopic  studies of 2-amino-3-cyano-4,5-diphenyl-furan derivatives. Balkan Physics Letters 5, 281-284.
  • Irimie, F. D, Paizs, Cs., Miclăuş, V., Afloroaei, C., Toşa, M. I., Damian, G. (1997): Mass Spectrometry of some new 5-hydroxymetyl-furyl-benzothiazoles obtained through cells catalysis. Balkan Physics Letters 5, 227-241.
  • Iliescu, T., Irimie F. D., Bolboacă M., Paizs Cs., Bratu I., Păcurariu R., Kiefer W. (2002): Structure and Vibrational Frequencies of 5-(4-bromo-phenyl)furan-2-carbalehyde: density functional theory studies. Studia Universitas Babeş-Bolyai, Physica, 47(2), 19-25.
  • Iliescu, T., Irimie F. D., Bolboacă M., Paizs Cs., Bratu I., Păcurariu R., Kiefer W. (2002): Surface-enhanced Raman Spectroscopy of 5-(4-bromo-phenyl)furan-2-carbalehyde on silver soil. Studia Universitas Babeş-Bolyai, Physica, 47(2), 13-18.

·        Irimie, F. D., Paizs, Cs., Toşa, M. I., Majdik, C., Moldovan, P., Căprioară, M., Neacşu, M. (2000): Cannizarro reaction in the phenothiazine series. Studia Universitatis Babeş-Bolyai, Chemia 45, 39-46.

·        Irimie F. D., Paizs, Cs., Toşa, M. I., Majdik, C., Moldovan, P. (2000): Mass spectrometry of some new derivates of 10-Pentyl-10H-phenothiazine. Studia Universitatis Babeş-Bolyai, Chemia 45, 29-38.

·        Irimie, F. D., Paizs, Cs., Toşa, M. I., Majdik, C., Moldovan, P., Mişca, R., Căprioară, M., Neacşu, M. (2000): Bioorganic reduction of some 5-phenyl-furan-2-carbaldehyde mediated by baker’s yeast. Studia Universitatis Babeş-Bolyai, Chemia 45, 23-28.

  • Lovász, T., Paizs, Cs., Cristea, I., Irimie, F. D. (1998): Synthesis and stereochemistry of some 4-furylidene-1-pyrimidinzl-2-pyrazolin-5-ones. Studia Universitatis Babeş-Bolyai, Chemia 43, 145-148.
  • Svistunenko, Dimitri A.; Reeder, Brandon J.; Wankasi, Mieebi M.; Silaghi-Dumitrescu, Radu; Cooper, Chris E. Rinaldo, Serena; Cutruzzolà, Francesca; Wilson, Michael T. Interaction of Aplysia limacina metmyoglobin with hydrogen peroxide.  Dalton Transactions, (2007), 10.1039/b615770j.
  • Silaghi-Dumitrescu, Radu; Reeder, Brandon; Nicholls, Peter; Cooper, Chris E.; Wilson, Michael T. Ferryl haem protonation gates peroxidatic reactivity in globins.  Biochemical Journal, (2007), 10.1042/BJ20061421.
  • Schwartz, Jennifer K.; Liu XF; Albetel AN; Silaghi-Dumitrescu, Radu, Kurtz,  Donald M, Jr.; Theil, Elizabeth C; Solomon, Edward I; Structure/function correlations in binuclear non-heme ferrous sites: Specific characterization of the active sites in m-Ferritin and nitric oxide reductases    Abstracts of Papers, 231st ACS National Meeting, United States, March 26, 2006  (2006),     INOR-89
  • Silaghi-Dumitrescu, Radu. Hemes Revisited by Density Functional Approaches. 2. A Paradigm for Axial Ligation In Hemoproteins.    Studia Universitatis Babes-Bolyai, Chemia (2006),  in press.
  • Silaghi-Dumitrescu, Radu. Fe(IV)-Fe(II) electromerism in hemoprotein complexes: implications for ferryl chemistry.    Proc.  Rom. Acad. Series B (2006),  in press.
  • Silaghi-Dumitrescu, Radu; Silaghi-Dumitrescu, Ioan; Editorial – special issue on Computational Inorganic Chemistry.  Chemtracts – Inorganic Chemistry (2005), 50, 11-16.
  • Silaghi-Dumitrescu, Radu; Silaghi-Dumitrescu, Ioan; Computational Inorganic Chemistry – a useful tool, and more.  Chemtracts – Inorganic Chemistry (2005), 684-708.
  • Isaza, Clara E.; Silaghi-Dumitrescu, Radu; Iyer, Ramesh B.; Kurtz, Donald M. Jr.; Chan, Michael K. Structural Basis for O2 Sensing by the Hemerythrin-like Domain of a Bacterial Chemotaxis Protein: Substrate Tunnel and Fluxional N Terminus.   Biochemistry, (2006), 45(30), 9023-9031.
  • Dunne, Jacqueline; Caron, Alexis; Menu, Patrick; Alayash, Abdu I.; Buehler, Paul W.; Wilson, Michael T.; Silaghi-Dumitrescu, Radu; Faivre, Beatrice; Cooper, Chris E. Ascorbate removes key precursors to oxidative damage by cell free hemoglobin in vitro and in vivo.  Biochemical Journal, (2006), 399(3), 513-24.
  • Silaghi-Dumitrescu, Radu; Copper-containing nitrite reductase: a DFT study of nitrite and nitric oxide adducts.  Journal of Inorganic Biochemistry, (2006), 100(3), 396-402.
  • Silaghi-Dumitrescu, Radu; Silaghi-Dumitrescu, Ioan; DFT and the electromerism in complexes of iron with diatomic ligands.  Journal of Inorganic Biochemistry, (2006), 100(1), 161-166.
  • Silaghi-Dumitrescu, Radu; Cooper, Chris E., Transient species involved in catalytic dioxygen/peroxide activation by hemoproteins: possible involvement of protonated compound I species.  Dalton Transactions, (2005), 3477-3482.
  • Iyer, Ramesh B.; Silaghi-Dumitrescu, Radu; Lanzilotta, William N.; Kurtz, Donald M.  Novel non-heme diiron bacterial peroxidases.    Abstracts of Papers, 229th ACS National Meeting, San Diego, CA, United States, March 13-17, 2005  (2005),     INOR-556
  • Iyer, Ramesh,* Silaghi-Dumitrescu, Radu,* Lanzilotta, William N. Kurtz, Donald M. Jr.  High-resolution crystal structures of Desulfovibrio vulgaris (Hildenborough) nigerythrin: facile, redox-dependent iron movement, domain interface variability, and peroxidase activity in the rubrerythrins   J. Biol. Inorg. Chem. (2005), 10, 407-416. (*authors marked “contributed equally to this work”)
  • Silaghi-Dumitrescu, Radu, Kurtz, Donald M. Jr., Ljungdahl,| Lars G., Lanzilotta, William N.  X-ray Crystal Structures of Moorella thermoacetica FprA. Novel Diiron Site Structure and Mechanistic Insights into a Scavenging Nitric OxideReductase.   Biochemistry, (2005), 44(17), 6492-6501.
  • Silaghi-Dumitrescu, Radu. A density functional study of heme-peroxynitrite adducts.  J. Mol. Struct. THEOCHEM, (2005), 722, 233-237.
  • Silaghi-Dumitrescu, Radu. “High-valent” ferryl-oxo complexes: how “high” are they really?    Studia Universitatis Babes-Bolyai, Chemia (2005),  50, 17-21.
  • Silaghi-Dumitrescu, Radu. Discontinuum between ferrous-superoxo and ferric-peroxo in heme [FeO2]9 complexes?    Studia Universitatis Babes-Bolyai, Chemia (2005),  in press.
  • Silaghi-Dumitrescu, Radu. Nitrile hydration by the cobalt-containing nitrile hydratase. DFT investigation of the mechanism    Revista de Chimie  (2005), 56(4), 359-362.
  • Silaghi-Dumitrescu, Radu; Ng, Kim Yong; Viswanathan, Rathinam, Kurtz, Donald M. Jr. A Flavo-diiron protein from Desulfovibrio vulgaris with oxidase and nitric oxide reductase activities. Evidence for an In vivo nitric oxide scavenging function.  Biochemistry, (2005), 44(9), 3572-9.
  • Das, Amaresh; Silaghi-Dumitrescu, Radu; Ljungdahl, Lars G.; Kurtz, Donald M., Jr., Cytochrome bd oxidase, oxidative stress and dioxygen tolerance of the strictly anaerobic bacterium, Moorella thermoacetica.  Journal of Bacteriology, (2005), 187(6), 2020-2029.
  • Kurtz, Donald M.; Lanzilotta, William N.; Silaghi-Dumitrescu, Radu.  How microbes detoxify superoxide, hydrogen peroxide, and nitric oxide: The non-heme iron reductive paradigm.    Abstracts of Papers, 227th ACS National Meeting, Anaheim, CA, United States, March 28-April 1, 2004  (2004),     INOR-418
  • Silaghi-Dumitrescu, Radu. Factors controlling O-O bond cleavage in ferric-hydroperoxo complexes.    Proc.  Rom. Acad. Series B, (2004), 3, 155-163.
  • Silaghi-Dumitrescu, Radu. Bioorganometallic complexes relevant to the “push effect” in hemoproteins.    Proc.  Rom. Acad. Series B, (2004), 3, 149-154.
  • Silaghi-Dumitrescu, Radu. Bonding in ferric-oxo complexes.    Studia Universitatis Babes-Bolyai, Chemia (2004),  49(2), 235-240.
  • Silaghi-Dumitrescu, Radu; Linkage isomerism in nitrite reduction by cytochrome cd1 nitrite reductase.  Inorganic Chemistry (2004), 43(12), 3715-3718.
  • Silaghi-Dumitrescu, Radu; The nature of the “high-valent” complexes in the catalytic cycles of hemoproteins.  Journal of Biological Inorganic Chemistry (2004), 9, 471-476.
  • Silaghi-Dumitrescu, Radu; The nitric oxide adducts of cytochrome cd1 nitrite reductase.    Revista de Chimie  (2004), 55, 496-498.
  • Silaghi-Dumitrescu, Radu; On the performance of the PM3 semiempirical method with heme complexes relevant to dioxygen and peroxide activation.    Revista de Chimie (2004), 55, 304-307.
  • Silaghi-Dumitrescu, Radu; Heme ferrous-hydroperoxo complexes: some theoretical considerations.    Archives of Biochemistry and Biophysics (2004), 424, 137-140.
  • Silaghi-Dumitrescu, Radu; Silaghi-Dumitrescu, Ioan. Hemes revisited by density functional approaches. 1. The axial ligand and the dioxygen-peroxo chemistry.    Revue Roumaine de Chimie (2004), 3-4, 257-268.
  • Silaghi-Dumitrescu, Radu; Amthor, Stephan; Paizs, Csaba; Majdik, Cornelia; Tosa, Monica; Moldovan, Paula; Sas, Angela; Tamas, Liana;  Irimie, Florin-Dan. Horseradish peroxidase - catalyzed oxidation of water - insoluble phenothiazines.    Studia Universitatis Babes-Bolyai, Chemia (2003),  48, 165.
  • Kurtz, Donald M., Jr.;  Emerson, Joseph P; Silaghi-Dumitrescu, Radu; Kung, Irene; Das, Amaresh; Ljungdahl, Lars; How microbes detoxify superoxide, hydrogen peroxide and nitric oxide. The non-heme iron reductive paradigm          Journal of Inorganic Biochemistry (2003),  96, 69.
  • Kurtz, Donald M., Jr.;  Silaghi-Dumitrescu, Radu; Das, Amaresh; Jameson, Guy; Ljungdahl, Lars; Huynh, Boi Hanh  A non-heme iron nitric oxide reductase that protects against nitrosative stress in acetogenic bacteria    Journal of Inorganic Biochemistry  (2003),  96, 174.
  • Silaghi-Dumitrescu, Radu; Kurtz, Donald M., Jr.  High-resolution crystal structures and spectroscopy of native and Compound I Cytochrome c Peroxidase            Chemtracts – Inorganic Chemistry (2003), 16, 722-728 – Commentary.
  • Silaghi-Dumitrescu, Radu; Irimie, Florin-Dan; Paizs, Csaba; Majdik, Cornelia; Tosa, Monica; Moldovan, Paula; Sas, Angela; Tamas, Liana.  Horseradish peroxidase catalyzed oxidation of some benzyl-type alcohols.    Studia Universitatis Babes-Bolyai, Chemia  (2003),  48, 177-182.
  • Silaghi-Dumitrescu, Radu; Kurtz, Donald M., Jr.  Tuning the electronic structure of octahedral iron complexes {FeL(X)} (L = 1-alkyl-4,7-bis(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane, X = Cl, CH3O, CN, NO): the S = 1/2 - S = 3/2 spin equilibrium of {FeLPr(NO)}.    Chemtracts – Inorganic Chemistry (2003), 16(8), 468-473 – Commentary.
  • Silaghi-Dumitrescu, Radu.  Nitric oxide reduction by heme-thiolate enzymes (P450nor): A reevaluation of the mechanism.    European Journal of Inorganic Chemistry (2003),   (6), 1048-1052.
  • Silaghi-Dumitrescu, Radu; Coulter, Eric D.; Das, Amaresh; Ljungdahl, Lars G.; Jameson, Guy N. L.; Huynh, Boi Hanh; Kurtz, Donald M., Jr.  A flavodiiron protein and high molecular weight rubredoxin from Moorella thermoacetica with nitric oxide reductase activity.    Biochemistry (2003), 42(10),  2806-2815.
  • Silaghi-Dumitrescu, Radu; Silaghi-Dumitrescu, Ioan; Coulter, Eric D.; Kurtz, Donald M., Jr.  Computational study of the non-heme iron active site in superoxide reductase and its reaction with superoxide.    Inorganic Chemistry (2003), 42(2), 446-456.
  • Silaghi-Dumitrescu, Luminita; Silaghi-Dumitrescu, Radu; Blake, Alexander J; Cooke, Paul A.; Sowerby, D. Bryan, Chlorination of (AsPh2)2O: Supramolecular structure of dihydroxodiphenylarsonium hydrogensulfate [AsPh2(OH)2] [HOSO3], Revue Roumaine de Chimie (2002), 47(10-11), 1063-1068.
  • Irimie, Florin-Dan; Paizs, Csaba; Majdik, Cornelia; Tosa, Monica; Misca, Radu; Silaghi-Dumitrescu, Radu.  Bioorganic synthesis of some (5-benzothiazol-2-yl-furan-2-yl)-methanols in cell catalysis using Saccharomyces cerevisiae.    Heterocyclic Communications (2002), 8(5), 489-492.
  • Silaghi-Dumitrescu, Radu; Silaghi-Dumitrescu, Ioan; Coulter, Eric D.; Emerson, Joseph P; Kurtz, Donald M., Jr.  Computational study of the non-heme iron active site in superoxide reductase and its reaction with superoxide.    Journal of Inorganic Biochemistry (2001), 86(1), 432.
  • Silaghi-Dumitrescu, Luminita; Silaghi-Dumitrescu, Ioan; Silaghi-Dumitrescu, Radu; Haiduc, Ionel; Blake, Alexander J.; Sowerby, D. Bryan.  Bromination of (AsPh2)2O: the structure of tribromo-diphenylarsenic(V).    Revista de la Sociedad Quimica de Mexico (2000), 44(2), 134-138.
  • Irimie, Florin-Dan; Paisz, Csaba; Joo, Francisc; Silaghi-Dumitrescu, Radu; Tosa, Monica; Majdik, Cornelia.  Biocatalytical reduction of some 5-(carboxyethyl-phenyl)-furyl-2-carboxaldehydes mediated by baker's yeast.    Progress in Catalysis (1999), 8(2), 70-73.
  • Irimie, Florin-Dan; Paizs, Csaba; Joo, Francisc; Silaghi-Dumitrescu, Radu; Tosa, Monica; Majdik, Cornelia.  Bioorganic reduction of some 5-phenyl-furyl-2-carboxaldehydes mediated by bakers' yeast.    Roumanian Biotechnological Letters (1999), 4(1), 71-74.
  • Irimie, Florin-Dan; Paizs, Csaba; Silaghi-Dumitrescu, Radu; Damian, G.; Majdik, Cornelia; Tosa, Monica.  Mass spectrometry of some new 2-hydroxymethyl-5-phenyl-furans obtained through cell catalysis.    Studia Universitatis Babes-Bolyai, Chemia (1998),  43(1-2),  173-177.
  • Majdik, Cornelia; Irimie, Florin-Dan; Paizs, Csaba; Silaghi-Dumitrescu, Radu; Joo, Francisc; Tosa, Monica.  Synthesis and reduction of some nitro-benzofurans.    Studia Universitatis Babes-Bolyai, Chemia (1998), 43(1-2), 115-120.
  • Irimie, Florin-Dan; Paizs, Csaba; Chender, C.; Joo, Francisc; Silaghi-Dumitrescu, Radu; Majdik, Cornelia; Tosa, Monica.  Furyl-benzothiazoles. Synthesis and reactivity.    Studia Universitatis Babes-Bolyai, Chemia (1998), 43(1-2), 109-114.
  • Silaghi-Dumitrescu, Radu; Paisz, Csaba; Irimie, Florin-Dan; Joo, Francisc; Majdik, Cornelia; Tosa, Monica.  Biotransformation of nitroso naphthols bioassisted by Baker's yeast.    Studia Universitatis Babes-Bolyai, Chemia (1998), 43(1-2),  83-90.

 

Links:

Local:

The Biochemistry group at the Chemistry Department, UBB

The Chemistry Department, UBB

The .Babes-Bolyai. University

 

Relevant Romanian institutions:

The Romanian Academy

 

Romanian chemistry/biochemistry journals

Studia Universitatis Babes-Bolyai

Revista de Chimie

Revue Roumaine de Chimie

Proceedings of the Romanian Academy