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1

The intercalation of imidazoacridinones into DNA induces conformational changes in their side chain.

100%

Mazerski J. , Muchewicz K.

Acta Biochimica Polonica

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2000

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tom 47

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nr 1

65-78

EN

Imidazoacridinones (IAs) are a new group of highly active antitumor compounds. The intercalation of the IA molecule into DNA is the preliminary step in the mode of action of these compounds. There are no experimental data about the structure of an intercalation complex formed by imidazoacridinones. Therefore the design of new potentially better compounds of this group should employ the molecular modelling techniques. The results of molecular dynamics simulations performed for four IA analogues are presented. Each of the compounds was studied in two systems: i) in water, and ii) in the intercalation complex with dodecamer duplex d(GCGCGCGCGCGC)2. Significant differences in the conformation of the side chain in the two environments were observed for all studied IAs. These changes were induced by electrostatic as well as van der Waals interactions between the intercalator and DNA. Moreover, the results showed that the geometry of the intercalation complex depends on: i) the chemical constitution of the side chain, and ii) the substituent in position 8 of the ring system.

2

Glucosamine-6-phosphate synthase, a novel target for antifungal agents. Molecular modelling studies in drug design.

80%

Wojciechowski M. , Milewski S. , Mazerski J. , Borowski E.

Acta Biochimica Polonica

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2005

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tom 52

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nr 3

647-653

EN

Fungal infections are a growing problem in contemporary medicine, yet only a few antifungal agents are used in clinical practice. In our laboratory we proposed the enzyme L-glutamine : D-fructose-6-phosphate amidotransferase (EC 2.6.1.16) as a new target for antifungals. The structure of this enzyme consists of two domains, N-terminal and C-terminal ones, catalysing glutamine hydrolysis and sugar-phosphate isomerisation, respectively. In our laboratory a series of potent selective inhibitors of GlcN-6-P synthase have been designed and synthesised. One group of these compounds, including the most studied N3-(4-methoxyfumaroyl)-l-2,3-diaminopropanoic acid (FMDP), behave like glutamine analogs acting as active-site-directed inactivators, blocking the N-terminal, glutamine-binding domain of the enzyme. The second group of GlcN-6-P synthase inhibitors mimic the transition state of the reaction taking place in the C-terminal sugar isomerising domain. Surprisingly, in spite of the fact that glutamine is the source of nitrogen for a number of enzymes it turned out that the glutamine analogue FMDP and its derivatives are selective against GlcN-6-P synthase and they do not block other enzymes, even belonging to the same family of glutamine amidotransferases. Our molecular modelling studies of this phenomenon revealed that even within the family of related enzymes substantial differences may exist in the geometry of the active site. In the case of the glutamine amidotransferase family the glutamine binding site of GlcN-6-P synthase fits a different region of the glutamine conformational space than other amidotransferases. Detailed analysis of the interaction pattern for the best known, so far, inhibitor of the sugar isomerising domain, namely 2-amino-2-deoxy-d-glucitol-6-phosphate (ADGP), allowed us to suggest changes in the structure of the inhibitor that should improve the interaction pattern. The novel ligand was designed and synthesised. Biological experiments confirmed our predictions. The new compound named ADMP is a much better inhibitor of glucosamine-6-phosphate synthase than ADGP.

3

The geometry of intercalation complex of antitumor mitoxantrone and ametantrone with DNA: Molecular dynamics simulations

80%

Mazerski J. , Martelli S. , Borowski E.

Acta Biochimica Polonica

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1998

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tom 45

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nr 1

1-11

4

N-Methyl-N-D-fructosyl amphotericin B methyl ester (MF-AME), a novel antifungal agent of low toxicity: Monomer/micelle control over selective toxicity.

61%

Cybulska B. , Gadomska I. , Mazerski J. , Grzybowska J. , Borowski E. , Cheron M. , Bolard J.

Acta Biochimica Polonica

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2000

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tom 47

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nr 1

121-131

EN

Rational chemical modification of amphotericin B (AMB) led to the synthesis of sterically hindered AMB derivatives. The selected optimal compound, N-methyl- N-D-fructosyl amphotericin B methyl ester (MF-AME) retains the broad spectrum of antifungal activity of the parent antibiotic, and exhibits a two orders of magnitude lower toxicity in vivo and in vitro against mammalian cells. Comparative studies of MF-AME and AMB comprising the determination of the spectroscopic properties of monomeric and self-associated forms of the antibiotics, the investigation of the influence of self-association on toxicity to human red blood cells, and of the antibiotic-sterol interaction were performed. On the basis of the results obtained it can be assumed that the improvement of the selective toxicity of MF-AME could in part be a consequence of the diminished concentration of water soluble oligomers in aqueous medium, and the better ability to differentiate between cholesterol and ergosterol.