V Politi

University of Rome Tor Vergata, Roma, Latium, Italy

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Publications (14)33.57 Total impact

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    ABSTRACT: We report a molecular dynamics simulation study of a zinc-protease--gelatinase A or MMP2--which is a major target for drug design, being involved in tumor metastasis and other degenerative diseases. Two structures have been employed as starting conditions, one based on the crystal of multi-domain proMMP2, the other consisting of the catalytic domain only. The overall fold of the two models is maintained over the 1260 ps trajectory, enabling us to analyze correlations of fluctuations among domains, and to observe the presence of correlations within the catalytic domain in the multi-domain enzyme only, hence due to the presence of hemopexin and fibronectin domains. In the multi-domain protein, two cavities are conserved over the trajectory, one of them pointing to a key region, a crevice surrounding the catalytic zinc. The other one is localized across the three domains of the MMP2 metalloproteinase. These areas are partially covered by the propeptide in the crystal structure of proMMP2. We propose a model of MMP2-collagen interaction that involves both identified cavities and takes into account the inter/intra domain cross-correlations.
    Journal of Computer-Aided Molecular Design 12/2003; 17(12):837-848. DOI:10.1023/B:JCAM.0000021883.44532.75 · 2.78 Impact Factor
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    ABSTRACT: The cleavage of bovine collagen I by neutrophil collagenase MMP-8 has been followed at pH 7.4, 37 degrees C. The behavior of the whole enzyme molecule (whMMP-8), displaying both the catalytic domain and the hemopexin-like domain, has been compared under the same experimental conditions with that of the catalytic domain only. The main observation is that whMMP-8 cleaves bovine collagen I only at a single specific site, as already reported by many others (Mallya, S. K., Mookhtiar, K. A., Gao, Y., Brew, K., Dioszegi, M., Birkedal-Hansen, H., and van Wart, H. E. (1990) Biochemistry 29, 10628-10634; Knäuper, V., Osthues, A., DeClerk, Y. A., Langley, K. A., Bläser, J., and Tschesche, H. (1993) Biochem. J. 291, 847-854; Marini, S., Fasciglione, G. F., De Sanctis, G., D'Alessio, S., Politi, V., and Coletta, M. (2000) J. Biol. Chem. 275, 18657-18663), whereas the catalytic domain lacks this specificity and cleaves the collagen molecule at multiple sites. Furthermore, a meaningful difference is observed for the cleavage features displayed by two forms of the catalytic domain, which differ for the N terminus resulting from the activation process (i.e. the former Met(80) of the proenzyme (MetMMP-8) and the former Phe(79) of the proenzyme (PheMMP-8)). Thus, the PheMMP-8 species is characterized by a much faster k(cat)/K(m), fully attributable to a lower K(m), suggesting that the conformation of the catalytic domain, induced by the insertion of this N-terminal residue in a specific pocket (Reinemer, P., Grams, F., Huber, R., Kleine, T., Schnierer, S., Piper, M., Tschesche, H., and Bode, W. (1994) FEBS Lett. 338, 227-233), brings about a better, although less discriminatory, recognition process of cleavage site(s) on bovine collagen I.
    Journal of Biological Chemistry 07/2002; 277(26):23123-30. DOI:10.1074/jbc.M110873200 · 4.60 Impact Factor
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    ABSTRACT: We have studied the effect of small molecular weight inhibitors of snake venom metalloproteinases (SVMP) and matrix metalloproteinases (MMPs) on the induction and effector phase of the contact hypersensitivity reaction (CHR) in a mouse model. Identification of nonsteroid small molecules is very important for the development of new anti-inflammatory drugs. The compounds that we tested were synthetically modified tripeptides (peptidomimetic compounds) POL-257, POL-509, POL-443, POL-491, and POL-647, with structures based on natural occurring peptides in snake venom. A well-known hydroxamate-based inhibitor of the MMPs, Batimastat (BB-94), was also used. We have shown that these peptidomimetics possess in vitro inhibitory activity against the MMP-2 (gelatinase-A), MMP-9 (gelatinase-B), and MMP-3 (stromelysin). They also inhibit metalloproteinases purified from the venom of Crotalus adamanteus and C. atrox snakes, which are very similar to the so-called A Desintegrine, A Metalloproteinase (ADAMs) enzymes. When injected intraperitonealy before the topical application of the contact sensitizer (picryl chloride) or before the challenge, these compounds significantly inhibited the development of CHR. BB-94 at doses 0.4 and 4 mg/kg before the sensitization or before the challenge almost completely abrogated the reaction. POL-257 and POL-443 were among the most active peptidomimetics tested. They inhibited the inflammatory reaction up to 70-80%, when applied either immediately before sensitization or before challenge. POL-509, a methylated derivative of POL-257, inhibited the CHR to 40-50% when administered at either challenge or sensitization. However, when applied 24 h before the challenge, it completely abrogated the inflammatory reaction. The results show that these small molecular weight peptidomimetic compounds, as well as BB-94, are able to significantly inhibit the CHR. This finding opens possibilities for using metalloproteinase inhibitors in the treatment of allergic contact dermatitis and other inflammatory diseases.
    International Immunopharmacology 05/2002; 2(5):699-710. DOI:10.1016/S1567-5769(02)00005-X · 2.71 Impact Factor
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    ABSTRACT: Metalloproteases are metalloenzymes secreted in the extracellular fluid and involved in inflammatory pathologies or events, such as extracellular degradation. A Zn(2+) metal, present in the active site, is involved in the catalytic mechanism, and it is generally coordinated with histidyl and/or cysteinyl residues of the protein moiety. In this study we have investigated the effect of both pH (between pH 4.8 and 9.0) and temperature (between 15 degrees C and 37 degrees C) on the enzymatic functional properties of the neutrophil interstitial collagenase (MMP-8), gelatinases A (MMP-2) and B (MMP-9), using the same synthetic substrate, namely MCA-Pro-Leu-Gly approximately Leu-DPA-Ala-Arg-NH(2). A global analysis of the observed proton-linked behavior for k(cat)/K(m), k(cat), and K(m) indicates that in order to have a fully consistent description of the enzymatic action of these metalloproteases we have to imply at least three protonating groups, with differing features for the three enzymes investigated, which are involved in the modulation of substrate interaction and catalysis by the enzyme. This is the first investigation of this type on recombinant collagenases and gelatinases of human origin. The functional behavior, although qualitatively similar, displays significant differences with respect to what was previously observed for stromelysin and porcine collagenase and gelatinase (Stack, M. S., and R. D. Gray. 1990. Arch. Biochem. Biophys. 281:257-263; Harrison, R. K., B. Chang, L. Niedzwiecki, and R. L. Stein. 1992. Biochemistry. 31:10757-10762). The functional characterization of these enzymes can have some relevant physiological significance, since it may be related to the marked changes in the environmental pH that collagenase and gelatinases may experience in vivo, moving from the intracellular environment to the extracellular matrix.
    Biophysical Journal 11/2000; 79(4):2138-49. DOI:10.1016/S0006-3495(00)76461-7 · 3.83 Impact Factor
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    ABSTRACT: The enzymatic processing of bovine collagen I by neutrophil collagenase (MMP-8) has been monitored at 37 degrees C, envisaging the occurrence of multiple intermediate steps, following the initial cleavage, which leads to the formation of (1/4) and (3/4) fragments. Further, the first cleavage event has been investigated at 37 degrees C as a function of pH, and catalytic parameters have been obtained through a global analysis of steady-state kinetic data, such as to get an overall consistent picture of k(cat)/K(m), k(cat), and K(m). These data have been compared with those obtained from the catalysis by MMP-8 of two synthetic fluorogenic substrates under the same experimental conditions. The overall behavior can be accounted for by the existence of five protonating groups, which vary to a different extent their pK(a) values for the three substrates investigated. The main observation concerns the fact the two of these residues, which play a relevant role in the enzymatic activity of MMP-8, are relatively far from the primary recognition site, and they are coming into action only for large macromolecular substrates, such as bovine collagen I. This finding opens the question of appropriate testing for inhibitors of the enzymatic action of MMP-8, which must take into account, and also of these relevant interactions occurring only with natural substrates.
    Journal of Biological Chemistry 07/2000; 275(25):18657-63. DOI:10.1074/jbc.M000283200 · 4.60 Impact Factor
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    ABSTRACT: In the last few years, Indol-3-pyruvic acid (IPA) has been subjected to 5 pilot clinical trials in volunteers and a phase II study on patients affected by anxiety, with or without sleep problems. Overall, results indicated a very good safety profile, relief from anxiety and a better quality of sleep in patients treated with IPA. Moreover, the drug showed no withdrawal signs, but positive effects on mood, improving feelings of relaxation, calmness and happiness. The mechanism of action of IPA, depending on increased turnover of some indoles in the CNS, appears clearly distinct from that of benzodiazepines, suggesting that the drug might be used in the treatment of symptoms of mild anxiety and stress experienced by busy and anxious people.
    Advances in Experimental Medicine and Biology 02/1999; 467:227-32. · 2.01 Impact Factor
  • Immunology Letters 05/1997; 56:185-185. DOI:10.1016/S0165-2478(97)85742-2 · 2.37 Impact Factor
  • Advances in Experimental Medicine and Biology 02/1996; 398:291-8. · 2.01 Impact Factor
  • Advances in Experimental Medicine and Biology 02/1991; 294:603-5. · 2.01 Impact Factor
  • Advances in Experimental Medicine and Biology 02/1991; 294:299-308. · 2.01 Impact Factor
  • Advances in Experimental Medicine and Biology 02/1991; 294:515-8. · 2.01 Impact Factor
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    ABSTRACT: The effects of acute or repeated administration of indole-pyruvic acid (IPA), a keto-analogue of tryptophan (TRP), were studied in various brain areas of rats by measuring the changes of 5-hydroxytryptamine (5-HT) and of norepinephrine (NE) content and metabolism. The analgesic and sedative properties of the molecule were evaluated by measuring the tail-flick latency, the spontaneous activity and the potentiation of the barbiturate-induced sleep. Acute or repeated administrations of IPA (20 or 50 mg/kg) increased the utilization of 5-HT in the cortex, hippocampus, diencephalon and brain-stem of rats fed a standard laboratory diet. IPA, however, did not substitute TRP in rats fed a TRP-free diet. The administration of this keto-analogue resulted also in a decreased content of 3-methoxy-4-hydroxy-phenylglycol (MHPG) in the cortex and in the brain-stem, thus suggesting a decreased utilization of NE in these areas. Furthermore, IPA administration decreased the rats' spontaneous activity, increased the duration of barbiturate-induced sleep and increased the tail-flick time, thus indicating that it has sedative and analgesic properties.
    Pharmacological Research Communications 12/1987; 19(11):803-17. DOI:10.1016/0031-6989(87)90014-2
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    ABSTRACT: Synthesis is described of some peptides and peptide derivatives related to the N-terminal amino acid sequence of a pharmacologically active decapeptide (POL-236) recently isolated from Crotalus Atrox snake venom. The synthetic compounds were tested for hypotensive activity in anaesthetized normotensive rats. At the used doses all compounds failed to show the immediate hypotensive effect noted after POL-236 administration.
    Il Farmaco; edizione scientifica 08/1986; 41(7):508-14.
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    ABSTRACT: The presence of new hypotensive peptides, possibly not related to ACE inhibition, has been investigated on 66 snake venoms from crotalid, viperid and elapid families. Only the venom of Crotalus atrox showed a substantial amount of a new decapeptide, called POL-236, with the following aminoacid sequence: PYR-LEU-TRP-PRO-ARG-PRO-GLN-ILE-PRO-PRO. Pharmacological assays performed on the synthesized peptide revealed effects on blood pressure, probably derived from vascular and cardiac interferences.
    Peptides 02/1985; 6 Suppl 3:343-6. DOI:10.1016/0196-9781(85)90395-X · 2.61 Impact Factor