Enzio Ragg

University of Milan, Milano, Lombardy, Italy

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Publications (73)162.3 Total impact

  • 10/2012; DOI:10.1094/CPLEX-2011-1004-01W
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    ABSTRACT: The chemoenzymatic deacylation of ramoplanin A2 is described for the first time: ramoplanin A2 was Boc-protected and hydrogenated to Boc-protected tetrahydroramoplanin, which was subsequently deacylated using an acylase from Actinoplanes utahensis NRRL 12052. The chemoenzymatic process proceeded with 80% overall yield, which favourably compares with the previously described chemical deacylation.
    Bioorganic & medicinal chemistry letters 06/2012; 22(16):5283-7. DOI:10.1016/j.bmcl.2012.06.046 · 2.33 Impact Factor
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    ABSTRACT: Bovine β-casein and its C-terminal sequence (191–209) were previously shown to possess immunomodulatory properties in studies on partially purified peptides from hydrolysates, where minor amounts of contaminants may affect the cellular response. The inhibitory effect of β-casein and of eight C-terminus synthetic β-casein peptides on mitogen-induced spleen cell proliferation was compared. Use of synthetic peptides allowed the unambiguous and accurate identification that a seven amino acid sequence at the C-terminus, including a PFP motif, was sufficient for immunomodulation. Substitution of the last proline (P206) in the PFP motif with D-Pro had a negative impact on the immunosuppressory activity of all these short peptides, whereas substitution of P206 with structural analogues of proline had almost no impact. A relationship was found between the immunomodulatory properties and the structural features of these peptides, as assessed by various spectroscopic approaches, indicating a role of structure in eliciting the immunomodulatory activity of these peptides.
    International Dairy Journal 10/2011; 21(10):770-776. DOI:10.1016/j.idairyj.2011.04.012 · 2.30 Impact Factor
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    ABSTRACT: Bis-2,3-heteroarylmaleimides and polyheterocondensed imides joined through nitrogen atoms of the N,N'-bis(ethyl)-1,3-propanediamine linker were prepared from substituted maleic anhydrides and symmetrical diamines in good to satisfactory yields and short reaction times using microwave heating. The novel molecules were shown to inhibit proliferation of human tumor cells (NCI-H460 lung carcinoma) and rat aortic smooth muscle cells (SMCs) with variable potencies. Compound 11a, the most potent one of the series, showed IC(50) values comparable to those observed for the leading molecule elinafide in both cell lines, but with a higher selectivity toward human tumor cells. Compound 11a affected G1/S phase transition of the cell cycle, showed in vitro DNA intercalating activity and in vivo antitumor activity. A thorough structural analysis of the 11a-DNA complex was also made by mean of NMR and computational techniques.
    Bioorganic & medicinal chemistry 09/2011; 19(18):5291-9. DOI:10.1016/j.bmc.2011.08.016 · 2.95 Impact Factor
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    ABSTRACT: Lithium salts dissolved in ionic liquids (ILs) are interesting alternatives to the commonly used electrolytes for Li-ion batteries. In this study, the solution of Li [bis-(trifluoromethanesulfonyl)imide] (LiTFSI) in N-butyl-N-methylpyrrolidinium TFSI (PYR14TFSI) ionic liquid in the 0.1:0.9 molar ratio is studied by heteronuclear NOE and NMR diffusion measurements. The main purpose is to spot on the interions organization and mobility. NOE data support the existence of strongly coordinated Li+ species, whereas variable temperature measurements of the self-diffusion coefficients D show large, selective, and unexpected enhancement of Li+ mobility with T. The measured activation energy for Li+ diffusion is significantly larger than those of TFSI− and PYR14+. These findings can be related to the mechanism of Li+ diffusion in ILs based on disruption formation of the coordination shells of Li+ with TFSI anions rather than on the Brownian motion of the whole Li+ coordinated species.Keywords (keywords): ionic liquids; NMR spectroscopy; NOE; diffusion; lithium batteries
    Journal of Physical Chemistry Letters 01/2011; 2(3). DOI:10.1021/jz101516c · 7.46 Impact Factor
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 12/2010; 24(49). DOI:10.1002/chin.199349045
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    ABSTRACT: An understanding of the integrated relationships among the principal cellular functions that govern the bioenergetic reactions of an organism is necessary to determine how cells remain viable and optimise their fitness in the environment. Urease is a complex enzyme that catalyzes the hydrolysis of urea to ammonia and carbonic acid. While the induction of urease activity by several microorganisms has been predominantly considered a stress-response that is initiated to generate a nitrogen source in response to a low environmental pH, here we demonstrate a new role of urease in the optimisation of cellular bioenergetics. We show that urea hydrolysis increases the catabolic efficiency of Streptococcus thermophilus, a lactic acid bacterium that is widely used in the industrial manufacture of dairy products. By modulating the intracellular pH and thereby increasing the activity of β-galactosidase, glycolytic enzymes and lactate dehydrogenase, urease increases the overall change in enthalpy generated by the bioenergetic reactions. A cooperative altruistic behaviour of urease-positive microorganisms on the urease-negative microorganisms within the same environment was also observed. The physiological role of a single enzymatic activity demonstrates a novel and unexpected view of the non-transcriptional regulatory mechanisms that govern the bioenergetics of a bacterial cell, highlighting a new role for cytosol-alkalizing biochemical pathways in acidogenic microorganisms.
    PLoS ONE 11/2010; 5(11):e15520. DOI:10.1371/journal.pone.0015520 · 3.23 Impact Factor
  • E. Ragg · C. Ulbricht · R. Mondelli
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    ABSTRACT: Diagonalization of the [r] matrix is the first step in the solution of the differential equations
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 09/2010; 25(36). DOI:10.1002/chin.199436139
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 07/2010; 24(30). DOI:10.1002/chin.199330294
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    ABSTRACT: The perylenequinone pigments Elsinochrome B and C have been shown to be mixtures of diastereoisomers, elsinochrome B1 and B2, and elsinochrome C1 and C2. The axial chirality of the helical perylenequinone ring was established from the CD spectra as M(R) for the four pigments and for elsinochrome A. The absolute configuration of the alicyclic ring and side-chain carbons was obtained from a detailed conformational analysis on the basis of NMR couplings and NOE experiments.
    Gazzetta chimica Italiana 07/2010; 123(30):131-136. DOI:10.1002/chin.199330245
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    ABSTRACT: Short double-stranded RNAs, which are known as short interfering RNA (siRNA), can be used to specifically down-regulate the expression of the targeted gene in a process known as RNA interference (RNAi). However, the success of gene silencing applications based on the use of synthetic siRNA critically depends on efficient intracellular delivery. Polycationic branched macromolecules such as poly(amidoamine) (PAMAM) dendrimers show a strong binding affinity for RNA molecules and, hence, can provide an effective, reproducible, and relatively nontoxic method for transferring siRNAs into animal cells. Notwithstanding these perspectives, relatively few attempts have been made so far along these lines to study in detail the molecular mechanisms underlying the complexation process between PAMAMs and siRNAs. In this work we combine molecular simulation and experimental approaches to study the molecular requirements of the interaction of RNA-based therapeutics and PAMAM dendrimers of different generations. The dendrimers and their siRNA complexes were structurally characterized, and the free energy of binding between each dendrimer and a model siRNA was quantified by using the well-known MM/PBSA approach. DOSY NMR experiments confirmed the structural in silico prediction and yielded further information on both the complex structure and stoichiometry at low N/P ratio values. siRNA/PAMAM complex formation was monitored at different N/P ratios using gel retardation assays, and a simple model was proposed, which related the amount of siRNA complexed to the entropy variation upon complex formation obtained from the computer simulations.
    Chemistry - A European Journal 05/2010; 16(26):7781-95. DOI:10.1002/chem.200903258 · 5.70 Impact Factor
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    ABSTRACT: Some optically active 3,4-dihydroisocoumarins have been obtained by enantioselective reduction of the corresponding aryl 2-carboxybenzyl ketones with the CBS catalyst. The ketones were obtained by condensation of the o-toluate carbanion with aldehydes followed by oxidation of the seconmdary alcohols. Enantiomeric excesses are variable depending on the substrate. This method has been applied to the synthesis of the sweet dihydroisocoumarin (R)-(+)-phyllodulcin, that was obtained in good enantiomeric excess as the 3’-benzyl-8-methyl ether. However, racemisation of this substrate occurred under several deprotecting conditions. A new synthesis of (+)-phyllodulcin is also described
    Gazzetta chimica Italiana 04/2010; 122(17):403-407. DOI:10.1002/chin.199317177
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2010; 22(3):349-349. DOI:10.1002/chin.199103349
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    ABSTRACT: The GB virus C or hepatitis G virus (GBV-C/HGV) is a single-stranded positive sense RNA virus that belongs to the Flaviviridae family. Recent years have seen the publication of numerous works in which coinfection with GBV-C/HGV and HIV has been associated with slower progression of the illness and a higher survival rate of patients once AIDS has developed. The mechanism by which the GBV-C/HGV virus has a "protective effect" in patients with HIV has still not been defined. Study of the interaction of the GBV-C/HGV and HIV viruses could lead to the development of new therapeutic agents for the treatment of AIDS. Given that the mechanism responsible for the beneficial effect exercised by the GBV-C/HGV virus in the course of HIV infection has not been defined, the present work is intended as a study of the structure and interactions between the fusion peptide of HIV-1, gp41(1-23), and synthetic peptide sequences of the E2 envelope protein of GBV-C/HGV using biophysical techniques. Our results highlight that the E2(269-286) sequence interacts with the target fusion peptide of HIV-1 and modifies its conformation.
    The Journal of Physical Chemistry B 05/2009; 113(20):7383-91. DOI:10.1021/jp900707t · 3.30 Impact Factor
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    ABSTRACT: A water soluble derivative (2) of topopyrones was selected for NMR studies directed to elucidate the mode of binding with specific oligonucleotides. Topopyrone 2 can intercalate into the CG base pairs, but the residence time into the double helix is very short and a fast chemical exchange averaging occurs at room temperature between the free and bound species. The equilibria involved become slow below room temperature, thus allowing to measure a mean lifetime of the complex of ca. 7 ms at 15 degrees C. Structural models of the complex with d(CGTACG)(2) were developed on the basis of DOSY, 2D NOESY and (31)P NMR experiments. Topopyrone 2 presents a strong tendency to self-associate. In the presence of oligonucleotide a certain number of ligand molecules are found to externally stack to the double-helix, in addition to a small fraction of the same ligand intercalated. The external binding to the ionic surface of the phosphoribose chains may thus represents the first step of the intercalation process.
    Bioorganic & medicinal chemistry 01/2009; 17(2):484-91. DOI:10.1016/j.bmc.2008.12.005 · 2.95 Impact Factor
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    ABSTRACT: The effect of root-released compounds of transplastomic tobacco (Nicotiana tabacum) on the soil bacterial community structure, and their potential to support horizontal gene transfer (HGT) to bacteria have been studied. Soil microcosms were exposed to root-released compounds collected from transplastomic and non-transgenic tobacco cultivars. Cluster analysis of automated ribosomal intergenic spacer analysis (ARISA) profiles of the soil bacterial community after 48 h incubation grouped the transgenic cultivar apart from the non-transgenic, indicating that it had a rhizodeposition pattern different from the parental plants. However, these differences were less than between the two non-transgenic tobacco cultivars studied. NMR characterization of the root-released compounds showed some differences in chemical fingerprinting pattern between the transplastomic and the parental cultivar. However, the effect on bacterial community structure was transient, and tended to disappear after 96 h of incubation. The potential of root-released compounds as a source of transforming DNA for bacteria was investigated by using four potential recipient species. No transformants were obtained following exposure of all the recipients to the root-released compounds. Root-released compounds amended to transgene donor DNA decreased the transformation frequency of Acinetobacter baylyi strain ADP1200, while Azospirillum, Agrobacterium, and Sinorhizobium strains failed to develop competence also in the presence of an external added transgene source. Detection of plastid sequences by PCR suggested that a very low amount of fragmented plastid donor DNA was present in the root-released compounds.
    Environmental Biosafety Research 01/2008; 7(1):11-24. DOI:10.1051/ebr:2008002
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    ABSTRACT: In this work, we present a structural characterization of the putative fusion peptide E2(279-298) corresponding to the E2 envelope protein of the HGV/GBV-C virus by (1)H NMR, CD and MD studies performed in H(2)O/TFE and in lipid model membranes. The peptide is largely unstructured in water, whereas in H(2)O/TFE and in model membranes it adopts an helical structure (approximately 65-70%). The partitioning free energy DeltaG ranges from -6 to -7.5 kcal mol(-1). OCD measurements on peptide-containing hydrated and oriented lipid multilayers showed that the peptide adopts a predominantly surface orientation. The (1)H NMR data (observed NOEs, deuterium exchange rates, Halpha chemical shift index and vicinal coupling constants) and the molecular dynamics calculations support the conclusions that the peptide adopts a stable helix in the C-terminal 9-18 residues slightly inserted into the lipid bilayer and a major mobility in the amino terminus of the sequence (1-8 residues).
    Archives of Biochemistry and Biophysics 10/2007; 465(1):187-96. DOI:10.1016/j.abb.2007.05.024 · 3.04 Impact Factor
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    ABSTRACT: Bowman-Birk serine protease inhibitors are a family of small plant proteins, whose physiological role has not been ascertained as yet, while chemopreventive anticarcinogenic properties have repeatedly been claimed. In this work we present data on the isolation of a lentil (Lens culinaris, L., var. Macrosperma) seed trypsin inhibitor (LCTI) and its functional and structural characterization. LCTI is a 7448 Da double-headed trypsin/chymotrypsin inhibitor with dissociation constants equal to 0.54 nM and 7.25 nM for the two proteases, respectively. The inhibitor is, however, hydrolysed by trypsin in a few minutes timescale, leading to a dramatic loss of its affinity for the enzyme. This is due to a substantial difference in the kon and k*on values (1.1 microM-1.s-1 vs. 0.002 microM-1.s-1), respectively, for the intact and modified inhibitor. A similar behaviour was not observed with chymotrypsin. The twenty best NMR structures concurrently showed a canonical Bowman-Birk inhibitor (BBI) conformation with two antipodal beta-hairpins containing the inhibitory domains. The tertiary structure is stabilized by ion pairs and hydrogen bonds involving the side chain and backbone of Asp10-Asp26-Arg28 and Asp36-Asp52 residues. At physiological pH, the final structure results in an asymmetric distribution of opposite charges with a negative electrostatic potential, centred on the C-terminus, and a highly positive potential, surrounding the antitryptic domain. The segment 53-55 lacks the anchoring capacity found in analogous BBIs, thus rendering the protein susceptible to hydrolysis. The inhibitory properties of LCTI, related to the simultaneous presence of two key amino acids (Gln18 and His54), render the molecule unusual within the natural Bowman-Birk inhibitor family.
    FEBS Journal 10/2006; 273(17):4024-39. DOI:10.1111/j.1742-4658.2006.05406.x · 3.99 Impact Factor
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    ABSTRACT: An improved procedure for the microbial hydroxylations of dehydroepiandrosterone (DHEA, 1) and 15 beta,16 beta-methylene-dehydroepiandrosterone (2) was studied using whole cells of Botryodiplodia malorum and Colletotrichum lini. C. lini catalyzed 7 alpha- and 15 alpha-hydroxylation of 1 and 7 alpha-hydroxylation of 2, while B. malorum gave 7 beta-hydroxylation of both the substrates. The stability of the enzymatic activity was higher in the presence of co-substrates (i.e., glucose or mannitol) allowing for repeated batches of the biotransformations. The yields of 7 alpha,15 alpha-dihydroxy-1 production were improved obtaining 5.8 gl(-1) (recovered product) from 7.0 gl(-1) of substrate. The structures of the hydroxylated products were assigned by a combination of two-dimensional NMR proton-proton and proton-carbon correlation techniques.
    Steroids 07/2006; 71(6):429-34. DOI:10.1016/j.steroids.2006.01.014 · 2.72 Impact Factor

Publication Stats

960 Citations
162.30 Total Impact Points

Institutions

  • 1987–2012
    • University of Milan
      • • Department of Molecular Sciences Applied To Biosystems DISMA
      • • Department of AgriFood Molecular Sciences
      • • Faculty of Agriculture
      Milano, Lombardy, Italy
  • 2000–2010
    • Università degli studi di Parma
      Parma, Emilia-Romagna, Italy
  • 1991
    • National Research Council
      Roma, Latium, Italy