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Vincenzo Pavone

Publications and source records attributed to Vincenzo Pavone.

11 recordsLinked to original sources
PubMed2006

Critical role of the N-loop and beta1-strand hydrophobic clusters of RANTES-derived peptides in anti-HIV activity.

HIV initiates its infectious cycle by docking to CD4 and a chemokine receptor, most commonly CCR5. RANTES, a natural CCR5 ligand, is a potent inhibitor of HIV-1. Despite the lack of structural information on the RANTES-CCR5 complex, determinants of HIV blockade were previously identified within the RANTES N-loop and beta1-strand regions. A prototype N-loop/beta1-strand peptide, named R11-29, contains two terminal hydrophobic stretches separated by a central hydrophilic region. Here, the role of the terminal hydrophobic clusters was investigated by means of amino acid substitutions or deletions. Most hydrophobic residues in these clusters were shown to be fundamental for the anti-HIV activity. However, increasing the hydrophobicity of the two clusters using non-natural amino acids did not significantly improve the potency of the peptides. These results may provide instrumental knowledge for the rational design of RANTES-derivative molecules with increased anti-HIV activity.

Amino Acid Sequence↗
PubMed2006

MOPPEBVCAD chemotherapy with limited and conditioned radiotherapy in advanced Hodgkin's lymphoma: 10-year results, late toxicity, and second tumors.

PURPOSE: MOPPEBVCAD (mechlorethamine, vincristine, procarbazine, prednisone, epidoxirubicin, bleomycin, vinblastine, lomustine, doxorubicin, and vindesine) chemotherapy with limited radiotherapy was devised in 1987 to reduce late toxicity and second tumor incidence while trying to improve effectiveness through increases of dose intensity and dose density. Late results, toxicity, and second tumor incidence were reviewed in all the patients treated. EXPERIMENTAL DESIGN: The drugs of three previous alternating regimens [CAD (lomustine, melphalan, and vindesine), MOPP (mechlorethamine, vincristine, procarbazine, and prednisone), and ABV (doxorubicin, bleomycin, and vinblastine)] were intensified and hybridized, the cumulative dose of mechlorethamine was lowered, and irradiation was delivered to no more than two sites either bulky or partially responding to chemotherapy. RESULTS: A total of 307 previously untreated advanced-stage patients underwent MOPPEBVCAD chemotherapy. Radiotherapy was delivered to 118 of 307 patients (38%). Remission was complete in 290 patients (94%). With a median follow-up of 114 months, 10-year overall, disease-free, and failure-free survival rates were 79%, 84%, and 71%, respectively. Forty-two patients relapsed and 60 died. The causes of death were Hodgkin's lymphoma in 36 patients, second neoplasms in 12, cardiorespiratory diseases in 4, pulmonary diseases in 2, and unknown in 6. Sixteen second tumors (of which nine were myelodysplasia and/or acute leukemia) were diagnosed in all. Outside this series of 307 patients, MOPPEBVCAD obtained complete responses in 12 of 15 relapsed and 9 of 9 refractory patients who had previously been treated with other regimens. CONCLUSIONS: Clinical response and long-term results are very satisfactory, whereas the second tumor incidence was lower than would have been expected with MOPP analogues. Given its response/late toxicity balance, MOPPEBVCAD does not undermine the leading role of ABVD as first-line regimen but can be indicated as a very effective second-line conventional therapy.

Adolescent↗
PubMed2005

Artificial di-iron proteins: solution characterization of four helix bundles containing two distinct types of inter-helical loops.

Peptide-based models have an enormous impact for the development of metalloprotein models, as they seem appropriate candidates to mimic both the structural characteristics and reactivity of the natural systems. Through the de novo design of four-helix bundles, we developed the DF (Due Ferri) family of artificial proteins, as models of di-iron and di-manganese metalloproteins. The goal of our research is to elucidate how the electrostatic environment, polarity and solvent accessibility of the metal-binding site, influence the functional properties of di-iron proteins. The first two subsets of the DF protein family, DF1 and DF2, consist of two non-covalently associated helix-loop-helix motifs, which bind the di-metal cofactor near the center of the structure. The DF2 subset was designed to improve the properties of DF1: DF2 and DF2t have several changes in their sequences to improve solubility and metal ion access, as well as a change in the loop connecting the two helices. In order to evaluate how these changes affect the overall structure of the model proteins, we solved the NMR structures of the di-Zn(II) complexes of DF2 and DF2t, and compared these structures with those recently obtained from X-ray crystallography. Further, we examined the thermodynamic consequences associated with the mutations, by measuring the stability of DF2t in the presence of different metal ions, and comparing the results with the data already obtained for DF2. Taken together, analysis of all the data showed the importance of the turn conformation in the design and stability of four-helix bundle.

Amino Acid Sequence↗
PubMed2005

ABVD versus modified stanford V versus MOPPEBVCAD with optional and limited radiotherapy in intermediate- and advanced-stage Hodgkin's lymphoma: final results of a multicenter randomized trial by the Intergruppo Italiano Linfomi.

PURPOSE: In this multicenter, prospective, randomized clinical trial on advanced Hodgkin's lymphoma (HL), the efficacy and toxicity of two chemotherapy regimens, doxorubicin, vinblastine, mechlorethamine, vincristine, bleomycin, etoposide, and prednisone (Stanford V) and mechlorethamine, vincristine, procarbazine, prednisone, epidoxirubicin, bleomycin, vinblastine, lomustine, doxorubicin, and vindesine (MOPPEBVCAD), were compared with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) as standard therapy to select which regimen would best support a reduced radiotherapy program, which was limited to < or = two sites of either previous bulky or partially remitting disease (a modification of the original Stanford program). PATIENTS AND METHODS: Three hundred fifty-five patients with stage IIB, III, or IV HL were randomly assigned. Three hundred thirty-four patients were assessable for the study and received six cycles of ABVD (n = 122), three cycles of Stanford V (n = 107), or six cycles of MOPPEBVCAD (n = 106); radiotherapy was administered to 76, 71, and 50 patients in these three arms, respectively. RESULTS: The complete response rates for ABVD, Stanford V, and MOPPEBVCAD were 89%, 76% and 94%, respectively; 5-year failure-free survival (FFS) and progression-free survival rates were 78%, 54%, 81% and 85%, 73%, and 94%, respectively (P < .01 for comparison of Stanford V with the other two regimens). Corresponding 5-year overall survival rates were 90%, 82%, and 89% for ABVD, Stanford V, and MOPPEBVCAD, respectively. Stanford V was more myelotoxic than ABVD but less myelotoxic than MOPPEBVCAD, which had larger reductions in the prescribed drug doses. CONCLUSION: When associated with conditioned and limited (not adjuvant) radiotherapy, ABVD and MOPPEBVCAD were superior to Stanford V chemotherapy in terms of response rate and FFS and progression-free survival. Patients were irradiated less often after MOPPEBVCAD, but this regimen was more toxic. ABVD is still the best choice when it is combined with optional, limited irradiation.

Adolescent↗
PubMed2005

Artificial diiron proteins: from structure to function.

De novo protein design provides an attractive approach for the construction of models to probe the features required for the function of complex metalloproteins. These minimal models contain the essential elements believed necessary for activity of the protein. In this article, we summarize the design, structure determination, and functional properties of a family of artificial diiron proteins.

Amino Acid Sequence↗
PubMed2004

Miniaturized heme proteins: crystal structure of Co(III)-mimochrome IV.

Protein design provides an attractive approach to test the essential features required for folding and function. Previously, we described the design and structural characterization in solution of mimochromes, a series of miniaturized metalloproteins, patterned after the F-helix of the hemoglobin beta-chain. Mimochromes consist of two medium-sized helical peptides, covalently linked to the deuteroporphyrin. CD and NMR characterization of the prototype, mimochrome I, revealed that the overall structure conforms well to the design. However, formation of Delta and Lambda diastereomers was observed. To overcome the problem of diastereomer formation, we re-designed mimochrome I, by engineering intramolecular, interchain interactions. The resulting model was mimochrome IV: the solution structural characterization showed the presence of the Lambda isomer as a unique form. To examine the extent to which the stereochemical stability and uniqueness of mimochrome IV was retained in the solid state, the crystal structure of Co(III)-mimochrome IV was solved by X-ray diffraction, and compared to the solution structure of the same derivative. Co(III)-mimochrome IV structures, both in solution and in the solid state, are characterized by the following common features: a bis-His axial coordination, a Lambda configuration around the metal ion, and a predominant helical conformation of the peptide chains. However, in the crystal structure, intrachain Glu1-Arg9 ion pairs are preferred over the designed, and experimentally found in solution, interchain interactions. This ion pairing switch may be related to strong packing interactions.

Arginine↗
PubMed2003

Design of a new mimochrome with unique topology.

Peptide-based metalloprotein models represent useful systems to help understand how metalloproteins can support different functions, by the use of similar metal ion cofactors. In order to shed light on the role of the protein matrix in modulating the heme properties, we developed new models: mimochromes. They are pseudo-C(2) symmetric systems, composed of two helical peptides covalently linked to the deuteroporphyrin. The use of C(2) symmetry is particularly advantageous, because it simplifies the design, synthesis and characterization. However, it leaves the problem of possible diastereomeric forms. In the cobalt complex of the first derivative, mimochrome I, Lambda and Delta isomers were indeed experimentally observed. All the insights derived from the Co(III)-mimochrome I structure were used to obtain a re-designed molecule, mimochrome IV. The spectroscopic characterization of the iron and cobalt derivatives suggested the presence of the Lambda isomer as unique species. The NMR solution structure of the diamagnetic Co(III)-mimochrome IV confirmed the ability of the molecule to adopt a unique topology, and revealed the peptide chains to be in helical conformation, as designed. The insertion of intramolecular, inter-chain interactions was successful in favoring the formation of one of the two possible diastereomers. The stereochemically stable structure of mimochrome IV provides an attractive model for modulating the redox potential of the heme, by simple changing the peptide chain composition around the heme.

Cobalt↗
PubMed2003

Preorganization of molecular binding sites in designed diiron proteins.

De novo protein design provides an attractive approach to critically test the features that are required for metalloprotein structure and function. Previously we designed and crystallographically characterized an idealized dimeric model for the four-helix bundle class of diiron and dimanganese proteins [Dueferri 1 (DF1)]. Although the protein bound metal ions in the expected manner, access to its active site was blocked by large bulky hydrophobic residues. Subsequently, a substrate-access channel was introduced proximal to the metal-binding center, resulting in a protein with properties more closely resembling those of natural enzymes. Here we delineate the energetic and structural consequences associated with the introduction of these binding sites. To determine the extent to which the binding site was preorganized in the absence of metal ions, the apo structure of DF1 in solution was solved by NMR and compared with the crystal structure of the di-Zn(II) derivative. The overall fold of the apo protein was highly similar to that of the di-Zn(II) derivative, although there was a rotation of one of the helices. We also examined the thermodynamic consequences associated with building a small molecule-binding site within the protein. The protein exists in an equilibrium between folded dimers and unfolded monomers. DF1 is a highly stable protein (K(diss) = 0.001 fM), but the dissociation constant increases to 0.6 nM (deltadeltaG = 5.4 kcalmol monomer) as the active-site cavity is increased to accommodate small molecules.

Binding Sites↗
PubMed2003

The role of anthracyclines in combination chemotherapy for the treatment of follicular lymphoma: retrospective study of the Intergruppo Italiano Linfomi on 761 cases.

In order to elucidate the role of anthracycline based combination chemotherapy regimens for the treatment of follicular lymphoma we conducted a retrospective study on a large series of patients with a histologically confirmed diagnosis of follicular lymphoma. The Italian lymphoma intergroup (ILI) promoted a retrospective study of patients with follicular lymphoma treated in cooperative trials between 1985 and 1996. Six hundred and thirty three cases were treated with an anthracycline-containing regimen and 128 patients were treated without anthracyclines. The two groups were prognostically comparable; in particular, no difference was observed according to both IPI and ILI prognostic index. Results showed a complete remission (CR) rate for patients treated with anthracyclines was 69.2% and overall response rate was 92.5%. After a median follow-up of 51 months (54 months for patients still alive), the 5- and 10-year overall survival (OS) rates were 80 and 66%, respectively. Disease-free survival (DFS) and failure-free survival (FFS) rates at 5 years were 61 and 49%, respectively. In the group of patients treated with combination chemotherapy not including anthracyclines, the CR rate was 67.5% and the overall response rate was 85.4%. A longer OS (80% at 5 years) was observed in patients treated with anthracyclines compared to 67% OS rate in patients treated without anthracyclines (p = 0.0004). FFS was significantly longer in patients treated with anthracyclines (49 vs. 34% p = 0.006). Patients treated with anthracyclines with low or intermediate risk according to ILI prognostic index showed a significantly longer OS (p = 0.0001 andp = 0.0009, respectively); those in the high-risk group showed a trend for a longer survival. In conclusion, this retrospective study shows that patients with follicular lymphoma treated with an anthracycline containing regimen had a better outcome compared to patients treated with other combination regimens non including anthracyclines in terms of CRs, OS and FFS. On the basis of these results anthracycline-containing regimens (ACR) should be considered as the standard treatment of patients with advanced follicular lymphoma.

Anthracyclines↗
PubMed1996

Crystal and Molecular Structure of the [6-Deoxy-6-[(2-(4-imidazolyl)ethyl)amino]- cyclomaltoheptaose]copper(II) Ternary Complex with L-Tryptophanate. Role of Weak Forces in the Chiral Recognition Process Assisted by a Metallocyclodextrin.

The ternary copper(II) complex of 6-deoxy-6-[(2-(4-imidazolyl)ethyl)amino]cyclomaltoheptaose (CDhm) and L-tryptophanate (L-TrpO(-)) was characterized by ESR and X-ray diffraction. The solid state structure of [Cu(CDhm)(L-TrpO)](+) shows that the aromatic side chain of TrpO(-) is outside the cavity and that the two amino nitrogen atoms, one from the histamine molecule and one from the amino acidate, are in a cis disposition. The two amino nitrogens, the imidazole nitrogen, and the carboxylate oxygen atoms form the base of a square pyramid, which surrounds the copper(II) ion, a water molecule occupying an apical position. Atomic distances suggest for this complex that pi-pi and d-pi interactions could occur in the solid state. Morover, the [Cu(CDhm)(L-TrpO)](+) has a self-assembled structure in which a CDhm molecule behaves as host and as guest. The imidazole and the indole ring are directed into the cavity of an adjacent CDhm molecule from the wider cyclodextrin rim, thus forming a polymeric column structure. ESR spectra were run on the copper(II) ternary complexes with L- or D-tryptophanate and L- or D-alaninate in frozen aqueous solution and on the former pair of enantiomers in the solid state, as well. While in the case of the ternary complex with L- or D-alaninate no differences are observed in their frozen solution spectra, in the case of complexes with TrpO(-) subtle differences are found. These differences, which disappear when excess methanol is used, are ascribed to the presence of weak forces, such as hydrophobic or d-pi interactions.

Journal Article↗