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Biomedical subjects

L Masotti

Publications and source records attributed to L Masotti.

At least 91 records · Page 5Linked to original sources
PubMed1981

Ubiquinones: stereochemistry and biological implications.

Proton NMR and 13C-NMR studies on the configuration of CoQn homologues show that the polyisoprenoid side-chain is in the all-trans configuration and confers a higher degree of rigidity to the quinones with respect to the acyl-chains of the phospholipids within the membrane bilayer. The quinonoid ring appears to be specifically involved in the redox function of the coenzyme while the side-chain length only affects the lipophilicity of the molecule. LIS data show that the ring strongly interacts with metals as a consequence of the high pi-electron density on the carbonyls that is somewhat larger on the carbonyl oxygen to alpha to the isoprenoid chain.

Carbon Isotopes↗
PubMed1981

Effect of CoQ homologues on the fluidity of phospholipid bilayers a studied by fluorescence polarization of perylene.

The effect of Coenzyme Q analogues on the fluidity of egg lecithin bilayers was studied by fluorescence polarization of perylene. The parameter was clearly affected by the side-chain length of the quinones, by their concentration, and by their redox state. With increasing concentration, short-chain quinones decreased the bilayer fluidity, and did so to an even greater extent in their reduced state. On the contrary, long-chain analogues fluidized the bilayer, the effect being independent of their redox state. Such observations might explain the lower efficiency of short-chain quinones, as compared to the long-chain analogues, in restoring, in vitro, the respiratory activity of CoQ2-depleted mitochondria.

Benz(a)Anthracenes↗
PubMed1981

[Intermolecular interactions between fluorescent probes bound to linear DNA].

Intermolecular interactions of fluorescent probes bound to linear DNA. Several fluorescent probes can be widely used in determining the base content, the geometry and the possible conformational transitions of linear and circular DNAs in solution. Data are presented showing that Tb3+ and DAPI bind independently to DNA and can therefore be used to monitor the G+C and A+T content of the nucleic acid respectively.

Amidines↗
PubMed1980

Conformational studies on the gramicidin A transmembrane channel in lipid micelles and liposomes.

The interaction of gramicidin A with lysolecithin micelles and with lecithin liposomes is demonstrated by circular dichroism to result in several metastable conformational states. A stable state can be obtained after extensive heating when the gramicidin A was added dry or in ethanol solution to the phospholipid dispersion but the stable state is readily obtained when gramicidin A is added in a trifluoroethanol solution. The circular dichroism of the stable conformational states is characterized by negative ellipticity below 205 nm and principally by a positive 220 nm band on which is superposed a weak 230 nm band (the latter likely arising from tryptophan side chains). The stable conformational state is considered to be that of the functional transmembrane channel primarily on the basis of extensive studies on its interaction with sodium ions.

Circular Dichroism↗
PubMed1980

Terbium as a new probe to detect G+C content of DNA.

Tb3+ has been tested as a probe to determine G + C per cent composition of DNA. DAPI, a fluorescent dye specific for A + T bases, has been employed at the same time as a complementary probe. Using calf thymus DNA (G + C = 40%; A + T = 60%), it has been found that the binding of the two dyes is independent, and that one binding site every 12,5 nucleotides exists for Tb3+ and one binding site every 8.3 nucleotides for DAPI. The simultaneous use of Tb3+ and DAPI allows therefore the monitoring of A-T, G-C sequences.

Animals↗