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Biomedical subjects

V Pavone

Publications and source records attributed to V Pavone.

At least 127 records · Page 7Linked to original sources
PubMed1984

[Characteristics of the electrophoretic mobility of blasts from acute non-lymphoid leukemias].

The behaviour of electrophoretic mobility (E.M.) of the blast cells has been investigated in 15 cases of acute non lymphoid leukemias (A.N.L.L.), (eleven cases of M1 type and four M5 type). The fast and homogeneous E.M. of M5 type in comparison with M1 has been underlined. E.M. of M1 blasts has been reported in a wide range varying from a "normal" migration (similar to that of normal neutrophils and monocytes) to a "fast" one (similar to M5 type). It is suggested that M1 leukemic forms, morphologically recognizable as the same leukemic type, are different L.A.N.L. indeed.

Acute Disease↗
PubMed1984

Modified calmodulin calcium binding domain III. Solid phase synthesis, purification and 1H n.m.r. characterization.

The dodecapeptide Ac-Asp-Lys-Asp-Gly-Asn-Gly-Tyr-Ile-Ser-Ala-Ala-Gaba-OH is a modified calmodulin calcium binding domain III. The synthesis of the peptide by the solid phase method with a total protection scheme using PAM-resin is reported. The purified compound has been characterized by 1H n.m.r. spectroscopy, both in the presence and in the absence of calcium ions, at various pHs. No strong specific interaction seems to occur between the peptide and Ca++ ions in water solutions.

Binding Sites↗
PubMed1983

Structure of N-tert-butyloxycarbonyl-D-leucyl-L-phenylalanylethanolamide. An N alpha-protected analogue of the COOH-terminal dipeptide of linear gramicidins.

Solid state conformational analysis of N-tert-butyloxycarbonyl-D-leucyl-L-phenylalanylethanolamide (t-Boc-D-Leu-L-Phe-EA), an N alpha-protected analogue of the COOH-terminal dipeptide of linear gramicidins, carried out by x-ray diffraction, has indicated that the molecules are characterized by an N-H...O = C intramolecularly hydrogen-bonded chain reversal of the beta-turn II' type. One of the two independent molecules in the asymmetric unit shows an additional intramolecular hydrogen bond of the O-H...O = C type, linking the hydroxyl function of the COOH-terminal ethanolamide moiety to the carbonyl oxygen of the urethane N-protecting group. This is the first experimental evidence for a beta-turn conformation fused with the oxy analogue of an alpha-turn. The results of an investigation in a solvent of low polarity (deuteriochloroform), using infrared absorption and 1' nuclear magnetic resonance, strongly support the view that an intramolecularly hydrogen-bonded beta-turn conformation is the most populated conformation of t-Boc-D-Leu-L-Phe-EA molecules at high dilution. In the self-association process, taking place at high concentration, the urethane and peptide NH groups are involved as hydrogen-bonding donors.

Amino Acid Sequence↗
PubMed1983

First observation of a beta-turn conformation fused with the oxy-analogue of an alpha-turn: the molecular structure of a model peptide of the C-terminal part of gramicidin A.

The molecular structure of N-tert-butyloxycarbonyl-D-leucyl-L-phenylalanyl ethanolamide (t-Boc-D-Leu-L-Phe-EA), a protected analogue of the C-terminal dipeptide of the membrane-active linear antibiotic gramicidin A, has been determined by X-ray diffraction. One of the two independent molecules in the asymmetric unit is characterized by a chain reversal stabilized by an intramolecular, three-centre, double hydrogen bonding. It represents the first experimental evidence for a beta-turn conformation fused with the oxy-analogue of an alpha-turn.

Chemical Phenomena↗
PubMed1983

Acute lymphoblastic leukemia hand-mirror cells. Study of nine cases.

Acute lymphoblastic leukemia with hand-mirror cells (HMC) was diagnosed in nine adult patients. Blast HMC were seen only in the bone marrow (12-57% range). Cytochemical studies revealed a positive reaction to tartrate-sensitive acid phosphatase in the tail portion of the cells in seven cases, with a strong, localized cytoplasmic reaction in four. Leukemic cells lacked surface immunoglobulins and were E rosette negative in all cases. Normal levels of adenosine deaminase activity (ADA) were found in five of the seven patients. Electron microscope studies confirmed the hand-mirror shape of the cell. These HMC contained large numbers of mitochondria and microspikes in the handle portion of the cell. The patients failed to respond to initial conventional ALL chemotherapy, but the prolonged survival with passable health of the majority of these, despite their lack of complete remission, is emphasized.

Acid Phosphatase↗
PubMed1983

Protected 1-3 segment of the peptaibol antibiotics alamethicin and hypelcin. Solid-state and solution study of a stereochemically constrained linear peptide.

A study of the modes of folding and self-association of Z-Aib-L-Pro-Aib-OMe (the protected 1-3 segment of the peptaibol antibiotics alamethicin and hypelcin) in the solid state was performed using i.r. absorption and X-ray diffraction. The stereochemically constrained tripeptide molecules adopt a 4 leads to 1 intramolecularly H-bonded form (beta-turn), where the single intramolecular H-bond is found between the peptide N-H group of the Aib3 residue and the urethane C = O group of the N-blocking benzyloxycarbonyl moiety. This folded structure is stabilized by an intermolecular H-bond between the urethane N-H group of the Aib1 residue and the peptide C = O group of the Pro2 residue of a symmetry related molecule. According to the i.r. absorption data, in CH2Cl2 and TMP solutions the same intramolecularly H-bonded form occurs as that found in solid state. Compared to the situation in the solid state, in CH2Cl2 and TMP solvation of the urethane N-H group replaces self-association (through the same N-H group). The results are also discussed in relation to those obtained for other protected -Aib-X-Aib- (X = Aib, L-Ala, L-Val) tripeptide segments of peptaibol antibiotics.

Alamethicin↗
PubMed1983

Studies on gliadin related peptides. I. Synthesis, purification and 1H n.m.r. characterization of the pentapeptide H-Tyr-(Gln)3-Pro-OH.

The pentapeptide H-Tyr-(Gln)3-Pro-OH has been recently postulated to be the basic repetitive unit of a sequential polypeptide contained in wheat bread alpha-gliadins, which are believed to be toxic factors in coeliac disease, gluten-dependent enteropathy. Solid-phase synthesis, purification and 1H n.m.r. characterization in water solution of this peptide are described.

Chromatography, High Pressure Liquid↗
PubMed1983

Bioorganic stereochemistry. A study of the peptide oxazolones from Z-(Aib)n-OH (n = 2-4) in the solid state.

An investigation of the preferred conformations and modes of self-association of the peptide oxazolones from Z(-Aib-)n-OH (n = 2-4) in the solid state has been performed by infrared absorption. More detailed information on the peptide oxazolone from Z(-Aib-)3OH(2) has been obtained using X-ray diffraction. In this compound the conformations of the first two Aib residues differ substantially, only the N-terminal one being found in the usual 3(10)-(or alpha-) helical region of the Ramachandran map. The C = N-bond of the oxazolone group is not conjugated with the lactone moiety. A very weak intermolecular interaction occurs between the urethane N-H and the carbonyl group of the oxazolone ring.

Aminoisobutyric Acids↗
PubMed1982

Peptaibol antibiotics: a study on the helical structure of the 2-9 sequence of emerimicins III and IV.

Solution conformations of the protected 2-9 segment of the peptaibol antibiotics emerimicins III and IV [alpha-aminoisobutyric acid (Aib)]3-L-Val-Gly-L-Leu-(Aib)2 and the related short sequences benzyloxy-(Aib)3-L-Val-OMe and benzyloxy-(Aib)3-L-Val-Gly-OMe have been investigated by circular dichroism studies. For the latter two compounds the structural preferences in the solid state have been assayed by x-ray diffraction analyses. The experimental data described here, along with those previously reported, support the view that the shortest Aib-containing segments (from tri- through pentapeptides) adopt the 3(10)-helical structure both in solution and in the solid state. In contrast, the octapeptide appears to adopt the alpha-helical structure in solution. The role of peptide chain length and specific amino acid sequences in stabilizing either of the two helical structures and hence their possible implications on the nature of the channel formed by peptaibol antibiotics in the membrane are also briefly outlined.

Alkylation↗
PubMed1982

[Electrophoretic mobility in acute null cell lymphoblastic leukemia].

The electrophoretic mobility (E.M.) (evaluated by cytopherometer) of human normal lymphocytes, shows a group of cells with a fast mobility, identifiable as T lymphocytes, and a second group with a slow mobility which can be characterized as B lymphocytes. Six cases of Acute Lymphoblastic Leukaemia characterized by negativity of immunological markers and classified as "Null Cells", and ten cases of B cell Chronic Lymphocytic Leukaemia were studied in order to investigate the E.M. behaviour of leukaemic cells and so a comparison with T and B normal lymphocytes migration. The blasts of Acute Lymphoblastic Leukaemia show a E.M. nearly similar to the fast group of normal lymphocytes, while lymphocytes of the B cell Chronic Lymphocytic Leukaemia migrate as the slow component of normal lymphocytes. The possibility of the utilization of cell E.M. in addition to immunological and cytochemical data, into the characterization of Acute Leukaemias is suggested.

Adolescent↗
PubMed1981

Structure of N-acetyl-D-alanyl-D-alanine hydrate. An analogue of the COOH-terminal segment of peptidoglycan of bacterial cell walls.

The solid state conformational analysis of Ac-D-Ala-D-Ala-OH.H2O, carried out by infrared absorption and X-ray diffraction, has indicated that the molecules are not extended in a regular beta conformation, but rather that they are partially folded, the phi, psi torsional angles of the COOH-terminal residue in particular being in the region of the left-handed alpha helix of the Ramachandran map. The acetylamino and peptide groups ar found in the usual trans conformation, the latter, however, exhibiting a deviation from rigid planarity. Only intermolecular hydrogen bonds occur in the crystal state. The solution conformational analysis, performed by infrared absorption and CD, has revealed that the amount of intramolecular N--H ... O==C hydrogen-bonded folded forms, if any, should be extremely small, even in deuteriochloroform at high dilution. In water, solvated, unordered species largely predominate.

Bacteria↗
PubMed1979

Conformational analysis of N-(tert.-amyloxycarbony-L-proline in the solid state and in solution.

The solid-state conformational analysis of t-AOC-L-Pro-OH has indicated that the molecules are not folded up to form an oxy-C7 peptide conformation, but rather that they are held together through intermolecular O-H .... 0 = C (urethane) hydrogen bonds. The tertiary amide bond is in the cis configuration. In solvents of high polarity strongly solvated species largely predominate. In cyclohexane solution non-associated and associated (involving the carboxyl C = O as the proton acceptor) species are simultaneously present. Obviously, the extent of association increases with increasing solute concentration. The amount of the oxy-C7 form, if any, should be extremely small. It is also demonstrated that CD measurements alone can lead to an incorrect picture of the conformational preferences of amino acid derivatives and small peptides in solution.

Adsorption↗
PubMedDate not supplied

Conformational rigidity versus flexibility in a novel peptidic neurokinin A receptor antagonist.

Neurokinin A receptor antagonists have been proposed as a new class of drugs for several applications in humans (asthma, intestinal motility, etc.). The rational design, synthesis, structural characterization and biological activity evaluation of a new potent, highly selective, long-lasting, peptide-based receptor antagonist are reported. The structure-activity relationship indicates that the conformational rigidity determines potency, specificity and especially the long life of the molecule in the living body. MEN10627 is the prototype of a new class of cyclic, peptide-based, neurokinin A receptor antagonists and it is a suitable candidate for clinical testing in humans.

Amino Acid Sequence↗
PubMedDate not supplied

Conformational behaviour of a cyclolinopeptide A analogue: two-dimensional NMR study of cyclo(Pro1-Pro-Phe-Phe-Ac6c-Ile-ala-Val8).

The cyclic octapeptide cyclo[-Pro1-Pro-Phe-Phe-Ac6c-Ile-ala-Val8-] [C8-Ac6c], containing the Pro1-Pro-Phe-Phe sequence, followed by a bulky helicogenic C alpha,alpha-dialkylated glycine residue Ac6c [1-aminocyclohexane-1-carboxylic acid), and a D-Ala residue at position 7 has been synthesized. This cyclic peptide is a deletion analogue of the naturally occurring cyclic nonapeptide cyclolinopeptide A (CLA). It has been designed with the aim of studying the role that the Ac6c and D-Ala residues play on the conformational behaviour of the whole molecule and their influence on the conformation of the Pro1-Pro-Phe-Phe sequence when compared with cyclolinopeptide A. C8-Ac6c has been investigated in chloroform and acetonitrile solutions by 2D NMR techniques. Only one set of sharp signals is observed in both solvents. This evidence strongly supports the hypothesis that only one conformational state exists in the chosen solvents. The interpretation of the experimental data points to the existence for C8-Ac6c of a very rigid structure stabilized by intramolecular hydrogen bonds. The measured NOE effects allow the calculation of internuclear distances, which have been used as restraints in molecular dynamic calculations. The proposed conformation of the molecule shows that the Pro-Pro-Phe segment retains the conformation observed in natural CLA both in solution and in the solid state and that the Ac6c residue indeed reinforces the ring rigidity not permitting the formation of any appropriate cavity in which inorganic cations could be complexed.

Amino Acid Sequence↗
PubMedDate not supplied

Solid-state and solution conformation of N-tert-butyloxycarbonyl-L-prolylglycine.

The occurrence of the oxy analogue in the trans-II 4 leads to 1 intramolecularly hydrogen-bonded nonhelical peptide conformation, recently proposed for t-BOC-L-Pro-Gly-OH in the solid state on the basis of infrared absorption evidence, has been disproved by x-ray diffraction analysis. This type of folding is also absent in polar solvents. However, in solvents of low polarity the presence of this folded form cannot be excluded.

Circular Dichroism↗