Wyniki wyszukiwania - BazTech

1

Wykorzystanie dżdżownic do oceny zanieczyszczenia gleb metalami ciężkimi

Broma M., Rajfur M., Kłos A., Duczmal K., Wacławek M.

Chemistry-Didactics-Ecology-Metrology

|

2009

|

R. 14, NR 1-2

57--64

PL

Celem przeprowadzonych przez nas badań była ocena możliwości wykorzystania dżdżownic do badania zanieczyszczenia gleb. Do badań wykorzystano dżdżownice Dendrobaena veneta pochodzące z Hodowli Dżdżownic „Ekagro Sp. z o.o.” ze Słupska oraz naturalnie występujące w środowisku dżdżownice ziemne Lumbricus terrestris. Zbadano sorpcję metali ciężkich przez badany gatunek dżdżownic, a także wpływ czasu ekspozycji na stężenie Cd, Pb i Zn w ich organizmach. Przeprowadzono również wstępne badania biomonitoringowe okolic Chmielowic k. Opola z wykorzystaniem naturalnie występującego na badanym obszarze gatunku dżdżownic. W dżdżownicach metodą absorpcyjnej spektrometrii atomowej (AAS) oznaczano stężenia: Cd, Cu, Mn, Ni, Pb i Zn.

EN

The aim of our investigations was assessment of earthworms usefulness in investigations of soil contamination. In our researches the earthworms Dendrobaena veneta (from Earthworms Farm „Ekagro Sp. z o.o.”, Słupsk, PL) and naturally occurring in environment earthworms Lumbricus terrestris were tested. The heavy metal type and exposition time influences on Cd, Pb and Zn concentrations in earthworms organism were investigated. The preliminary biomonitoring researches were conducted in the region of Chmielowice (Opole voivodship, south-western Poland). The concentrations of: Cd, Cu, Fe, Mn, Ni, Pb and Zn were determined in earthworms with atomic absorption spectrometry (AAS).

2

Consequences of Covalent and Non-Covalent Interactions on Conformational Preferences and pi-Electron Delocalization for the Substrate (Pyruvate) and Inhibitor (Oxamate) of Lactate Dehydrogenase - DFT Studies

Raczyńska E. D., Hallmann M., Duczmal K.

Polish Journal of Chemistry

|

2008

|

Vol. 82, nr 5

1077-1090

EN

Conformational preferences and pi-electron delocalization for the isolated substrate (pyruvate) and inhibitor (oxamate) of lactate dehydrogenase (LDH), their protonated forms, adducts with alkali metal cations, and complexes with imidazole and/or the guanidinium cation (models for His195 and Arg171 of the LDH pocket, respectively) have been investigated at the DFT(B3LYP)/6-31++G(d,p) level. Covalent and non covalent bonds in acids, adducts and complexes cause greater conformational changes for pyruvate than for oxamate. Delocalization of pi electrons for the OCO frag ments is similar for similar structures. For isolated anions, adducts and complexes, the HOMED(OCO) values are between 0.9 and 1.0. For protonated forms, the HOMED(OCO) val ues are re duced to 0.55-0.75. Delocalization of pi electrons for the CCO fragment in pyruvate and for the NCO fragment in oxamate in creases when the anions form covalent and non-covalent bonds with other ions and molecules. The HOMED(CCO) values vary from 0.1 to 0.5 forsigma-pi conjugated pyruvate, whereas the HOMED(NCO) values vary from 0.9 to 1.0 for n-pi conjugated oxamate.

3

Tautomeric Equilibria and pi-Electron Delocalization for the Substrate (Pyruvate) and Inhibitor (Oxamate) of Lactate Dehydrogenase - DFT Studies

Raczyńska E. D., Duczmal K., Hallmann M.

Polish Journal of Chemistry

|

2007

|

Vol. 81, nr 9

1655-1666

EN

Keto-enol tautomerism for the substrate (pyruvate) of lactate dehydrogenase (LDH) and amideiminol tautomerism for its inhibitor (oxamate) were studied at the DFT(B3LYP)/6-31++G(d,p) level. Both anions (and also both radicals) prefer the C=O forms, i.e. the keto and amide form, respectively. The OH forms (enolpyruvate and iminoloxamate) have higher Gibbs free energies. Their amounts in the tautomeric mixtures are larger than 0.01% for anions and lower than 0.001% for radicals. pi-Electron delocalization for OCO fragments is greater than that for XCO fragments for both anions and radicals.

4

Comparison of the Proton (H+) and Alkali Metal Ion (Li+, Na+ and K+) Binding Affinities of Pyruvate and Oxamate Anions in the Gas Phase. Quantum-Chemical Studies

Duczmal K., Hallmann M., Raczynska E., Gal F., Maria P.

Polish Journal of Chemistry

|

2007

|

Vol. 81, nr 5-6

1011-1020

EN

Proton affinity (PA), lithium, sodium and potassium cation affinities (CA) in the gas phase were estimated by Gaussian-2 (G2), Möller-Plesset (MP2) methods and/or hybrid density functional theory calculations (B3LYP) for pyruvate and oxamate anions. Comparison of these affinities shows that the COO– groups of both anions have similar basicities. Differences between their calculated PAs as well as between their calculated CAs are not larger than 3 kcal mol–1. Somewhat larger differences are evidenced for the formations of the alkali metal complexes with the cation located between the oxygen atoms of the alfaC=O and COO– groups for which the lithium, sodium and potassium cation affinities are larger for oxamate than for pyruvate (by 40.5 kcal mol–1 at theG2 level and by 60.5 kcal mol–1 at the DFT(B3LYP)/6-31++G** level). This is a consequence of the chelate effect on the cation binding seen on the calculatedmost stable structures of the adducts.

5

Keto_Enol Tautomerism in Pyruvic Acid-Theoretical (HF, MP2 and DTF in the Vacuo) Studies

Raczyńska E., Duczmal K., Darowska M.

Polish Journal of Chemistry

|

2005

|

Vol. 79 / nr 4

689-697

EN

Extended quantum-chemical calculations {HF, MP2, DFT(B3LYP) in vacuo} were performed for neutral pyruvic acid and its enol forms. Among various tautomers-rotamers considered, three keto (Tce, Tte and Cte) and six enol structures (E1-E6) are found to be thermodynamically stable. The stability order for the keto and enol isomers: Tce > Tte > Cte > E1 > E2 > E3, E4, E5 > E6 is the same at each level of computations. The keto Tce structure has the lowest Gibbs free energy (G). The G value of the most stable enol E1 structure is larger than those of the three keto structures by a few kcal mol-1.