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Biomedical subjects

G Cilento

Publications and source records attributed to G Cilento.

At least 55 records · Page 3Linked to original sources
PubMed1981

Quenching of enzyme-generated acetone phosphorescence by indole compounds: stereospecific effects of D- and L-tryptophan. Photochemical-like effects.

Indole compounds efficiently quench the acetone phosphorescence observed during the horseradish peroxidase catalyzed aerobic oxidation of isobutyraldehyde. Different types of Stern-Volmer plots are observed: linear, linear with two slopes, and downward- and upward-curved plots. The complexity probably stems from the operation of both dynamic and static quenching, coupled with different efficiencies of quenching of various acetone triplet populations. Binding to the enzyme may also occur, especially in the case of L-tryptophan. The different Stern-Volmer behavior of D- and L-tryptophan fully confirms that the acetone triplet is generated within the enzyme and not free in solution. This chiral discrimination toward an enzymically generated electronically excited species is novel. It is tentatively postulated that a long-range triplet-triplet exciton transfer occurs; the excited triplet indole then undergoes photochemical-like alterations.

Acetone↗
PubMed1980

Excited indole-3-aldehyde from the peroxidase-catalyzed aerobic oxidation of indole-3-acetic acid. Reaction with and energy transfer to transfer ribonucleic acid.

The horseradish peroxidase catalyzed aerobic oxidation of the auxin indole-3-acetic acid generates triplet indole-3-aldehyde in high yield. The excited species is quenched by oxygen with formation of singlet oxygen, which is responsible for the observed photon emission and can be trapped by suitable agents. tRNA dramatically enhances the emission as a result of energy transfer from triplet indole-3-aldehyde to a 4-thiouridine group in tRNA. Triplet indole-3-aldehyde also adds covalently to tRNA. The results provide a possible mechanism for the auxin-tRNA interaction in vivo.

Aldehydes↗
PubMed1978

DNA damage during the peroxidase-catalyzed aerobic oxidation of isobutanal.

The aerobic oxidation of isobutanal catalyzed by peroxidase, when carried out in the presence of DNA, produces alkali-sensitive bonds in this macromolecule. Neither the initial components of this reaction nor the final stable products are responsible for this effect. Since triplet acetone has been recently identified as an intermediate in this oxidation (Durán, N., Faria Oliviera, O.M.M., Haun, M. and Cilento, G. (1977) J. Chem. Soc. Chem. Commun., 442--443), this species is a likely candidate for the entity which brings about the lesions, via transfer of its electronic energy to DNA.

Aerobiosis↗