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Biomedical subjects

M Palumbo

Publications and source records attributed to M Palumbo.

At least 145 records · Page 8Linked to original sources
PubMed1981

3-Amino- and 3-oxy-derivatives of psoralen: preparation and interactions with DNA.

3-Amino- and 3-oxy-derivatives of psoralen, thus having electron-donating groups at the 3-position of the alpha-pyronic ring, were prepared and studied as regards their capacities of interaction and photoreaction with native DNA in vitro. Very interesting properties were shown especially by the 3-amino-derivatives, namely 3-amino-4'-methylpsoralen and 3-diethylaminoacetylamido-4'-methylpsoralen, having a very high photobinding capacity with DNA and behaving as pure, or fairly pure, monofunctional reagents. These properties appear to be quite suitable for the therapeutic treatment of psoriasis and other skin diseases characterized by an increased reproducing activity of epidermal cells.

Chemical Phenomena↗
PubMed1980

Inhibition of the cytochrome c/cytochrome c oxidase system by cytochrome c derivatives and related fragments.

The oxidation of ferrocytochrome c mediated by cytochrome c oxidase was investigated in the presence of ferricytochrome c, trifluoroacetyl-cytochrome c, the heme fragments Hse65-[1-65] and Hse80-[1-80] and their respective porphyrin derivatives, as well as carboxymethylated apoprotein and related fragments, polycations, salts and neutral additives. The inhibition of the redox reaction by salts and neutral molecules, even if in theoretical agreement with their effect on electrostatic interactions, may alternatively be interpreted in terms of hydrophobicity. The latter can account for the inhibitory properties of trifluoroacetylated ferricytochrome c, similar to those of ferricytochrome c. On the assumption that the inhibitory properties of some of the investigated derivatives monitor their binding affinities to the cytochrome c oxidase at the cytochrome c binding sites, the experimental results do not confirm a primarily electrostatic character for the cytochrome c/cytochrome c oxidase association process. Strong indication was found that the cytochrome c C-terminal sequence is critically involved in the complex formation. Conformational studies by circular dichroism measurements and IR spectroscopy in solution and in solid state respectively, show that some of the derivatives examined may possibly acqkuire in the binding process to the oxidase, as secondary structure similar to that present in the native cytochrome c.

Amino Acids↗
PubMed1975

Synthesis and conformational studies in solution of sequential copolypeptides: poly(L-prolyl-L-alpha-phenylglycyl-L-proline).

High molecular weight poly(L-porlyl-L-alpha-phenylglycyl-L-proline) was synthesized by condensation of L-prolyl-L-alpha-phenylglycyl-L-proline pentachlorophenyl ester in N,N-dimethylformamide. The solution properties of this material have been investigated by circular dichroism and 220-MHz nuclear magnetic resonance spectroscopy in solvents such as trifluoroethanol (F3EtOH), chloroform, trifluoroacetic acid (F3CCOOH), chloroform-F3CCOOH and F3EtOH-F3CCOOH mixtures. Ordered structures can be formed in F3EtOH and chloroform, which we believe to be similar to the poly-L-proline II form. The ordered form easily undergoes a conformational transition to an unordered form upon addition of small amounts of F3CCOOH to the chloroform solution. The ordered structure is not disrupted upon addition of 12 per cent F3CCOOH to a F3EtOH solution of the polypeptide.

Chloroform↗
PubMedDate not supplied

On the oxy analogues to the 4 leads to 1 intramolecularly hydrogen-bonded peptide conformations.

The occurrence of the oxy analogue to the type II' 4 leads to 1 intramolecularly hydrogen-bonded nonhelical peptide conformation, recently proposed for t-BOC-Gly-L-Pro-OH in the solid state by Deber on the basis of infrared absorption evidence, has been disproved by x-ray diffraction analysis. This type of folding is also absent in solvents of moderate or high polarity. The latter conclusion is in agreement with Deber's results. However, in solvents of low polarity this intramolecularly hydrogen-bonded form could account for the strong negative Cotton effect near 230 nm observed in the circular dichroism spectrum.

Binding Sites↗