Maria Louloudi

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The Zn(2+), Cd(2+), Hg(2+), Co(2+) and Ni(2+) ions produce zwitterionic type complexes with the ligands (L), 2-(alpha-hydroxy-benzyl)thiamine=HBT and 2-(alpha-hydroxy-cyclohexyl-methyl)thiamine = HCMT, of the type MLCl(3). The ligands are in the S conformation, the metals are bound to N(1), of the pyrimidine moiety of thiamine and the complexes have a(More)
To obtain structural information on the active site of thiamin-dependent enzymes in solution, we have studied the interactions of Cu(2+) ions with 2-(alpha-hydroxyethyl)thiamin pyrophosphate (HETPP), the pentapeptide Asp-Asp-Asn-Lys-Ile surrounding the thiamin pyrophosphate moiety in the transketolase enzyme, and the tertiary Cu(2+)-pentapeptide-HETPP(More)
Thiamine dependent enzymes catalyze ligase and lyase reactions near a carbonyl moiety. Chemical models for these reactions serve as useful tools to substantiate a detailed mechanism of action. This tutorial review covers all such studies performed thus far, emphasizing the role of each part around the active site and the conformation of the cofactor during(More)
Metal complexes of thiamine pyrophosphate (TPP) of the general formula [M2(TPPH)2Cl2]x4H2O (M = Zn2+, Cd2+) were isolated from methanolic solutions and characterized by elemental analysis, FT-IR, and multinuclear NMR spectroscopies. The data provide evidence for the bonding of the metals to the N(1') atom of the pyrimidine ring and to the pyrophosphate(More)
Mononuclear CuL and Cu(2L) complexes, where L is propyl-thiazol-2-ylmethylene-amine, covalently immobilized onto SiO2, can catalyze efficiently the oxidation of 3,5-di-t-butylcatechol (DTBC) to 3,5-di-t-butylquinone (DTBQ) by utilizing ambient O2 as oxidant. By increasing the loading of L on SiO2, the DTBQ formation can be improved up to 400% vs the(More)
This paper is a brief review of the detailed mechanism of action of thiamine enzymes, based on metal complexes of bivalent transition and post-transition metals of model compounds, thiamine derivatives, synthesized and characterized with spectroscopic techniques and X-ray crystal structure determinations. It is proposed that the enzymatic reaction is(More)
The sorption of a hydrophobic pesticide, thiram, on humic acid (HA) occurs via a specific pH-dependent binding of thiram at the deprotonated carboxylates of humic acid, forming a species thiram-[HACOO-] with K = 0.69. Similarly, thiram was sorbed by two model polycarboxylate-{SiO2COOH} materials via the formation of a surface species thiram-{SiO2COO-} with(More)
A novel material, PyrC350®, has been developed from pyrolytic-tire char (PyrC), as an efficient low-cost Arsenite [As(III)] adsorbent from water. PyrC350® achieves 31mgg-1 As(III) uptake, that remains unaltered at pH=4-8.5. A theoretical Surface Complexation Model has been developed that explains the adsorption mechanism, showing that in situ formed Fe3C,(More)
In this paper, it is reported that the histidine-silane derivative Boc-His(Boc)-CONH-(CH2)3Si(OEt)3 can be polymerized via the sol-gel method or can be grafted on a silica surface. The obtained organosilicas bear histidine molecules covalently bonded on the inorganic matrix. Their Cu(II) complexes have been evaluated as oxidation catalysts for the(More)