Medical Aspects of DNA-Porphyrin Interactions
About: This article is published in ChemInform.The article was published on 1991-02-26. It has received 159 citations till now. The article focuses on the topics: Porphyrin.
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TL;DR: This chapter discusses DNA and RNA cleavage by metal complexes and the synthesis of compounds that cleave nucleic acids should help in the design of potential therapeutic agents for the treatment of cancer and viral diseases.
Abstract: Publisher Summary This chapter discusses DNA and RNA cleavage by metal complexes. DNA and RNA cleavage, a very active field of research, has been developed in two main and complementary directions within the past decade: oxidative cleavage and hydrolysis. In general, the difference between the two different approaches are (1) the preparation of new chemical tools to study genomic DNA. The recognition sites of most of the restriction enzymes are often limited to palindromic sequences, and it is useful to have artificial nucleases able to cleave DNA at any desired sequence, and (2), the synthesis of compounds that cleave nucleic acids should help in the design of potential therapeutic agents for the treatment of cancer and viral diseases. The challenging development of new, efficient DNA and RNA cleavage agents can require a strong cooperation between chemists, biochemists, and molecular biologists.
327 citations
TL;DR: The data indicate that, in the complicated transition from a "live" to "dead" cell, the majority of cells have the metabolic activity and morphology characteristic of a live cell, and confirms that the singlet oxygen lifetime in a cell is much longer than hitherto believed.
Abstract: Singlet molecular oxygen, O2(a1Δg), has been detected from single neurons and HeLa cells in time-resolved optical experiments by its 1270 nm phosphorescence (a1Δg → X3Σ–g) upon irradiation of a photosensitizer incorporated into the cell. The cells were maintained in a buffered medium and their viability was assessed by live/dead assays. To facilitate the detection of singlet oxygen, intracellularH2O was replaced with D2O by an osmotic de- and rehydration process. The effect of this insult on the cells was likewise assessed. The data indicate that, in the complicated transition from a “live” to “dead” cell, the majority of our cells have the metabolic activity and morphology characteristic of a live cell. Quenching experiments demonstrate that the singlet oxygen lifetime in our cells is principally determined by interactions with intracellularwater and not by interactions with other cell constituents. The data indicate that in a viable, metabolically-functioning, and H2O-containing cell, the lifetime of singlet oxygen is ∼3 µs. This is consistent with our previous reports, and confirms that the singlet oxygen lifetime in a cell is much longer than hitherto believed. This implies that, in a cell, singlet oxygen is best characterized as a selective rather than reactive intermediate. This is important when considering roles played by singlet oxygen as a signaling agent and as a component in events that result in cell death. The data reported herein also demonstrate that spatially-resolved optical probes can be used to monitor selected events in the light-induced, singlet-oxygen-mediated death of a single cell.
250 citations
TL;DR: A voltammetric study of the interaction of TMAP with DNA on Hg electrode in ammoniacal buffer solution is described in this paper, where the results of samples determination by electrochemical method are consistent with those by UV-spectroscopy.
229 citations
TL;DR: A kinetic analysis of the cleavage data revealed that cleavage rates are in the order CoTMPyP > CoTBPyP > coTOPyP with the difference being due to different DNA affinities rather than differences in cleavage rate-constants.
Abstract: Utilizing linear dichroism (LD), circular dichroism (CD), and fluorescence energy transfer, the binding geometries of a series of Co(3+)-porphyrins and their free ligands were examined. The compounds studied were Co-meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (CoTMPyP) and its free ligand (H2-TMPyP), Co-meso-tetrakis(N-n-butylpyridinium-4-yl)porphyrin (CoTBPyP) and its free ligand (H2TBPyP), and Co-meso-tetrakis(N-n-octylpyridinium-4-yl)porphyrin (CoTOPyP). The two non-metalloporphyrins exhibit negative LD, having angles of roughly 75 degrees relative to the DNA helix axis. They also display negative CD and a significant contact energy transfer from the DNA bases. On the other hand, the three metalloporphyrins display orientation angles of roughly 45 degrees between the porphyrin plane and the helix axis of DNA. Furthermore, they exhibit positive CD and no contact energy transfer from DNA bases. These observations show that the metalloporphyrins are not intercalated whereas non-metalloporphyrins having four freely rotating meso-aryl groups intercalate between the base pairs of DNA. In the presence of KHSO5, the cobalt porphyrins cleave closed circular PM2 DNA in a single strand manner, i.e., a single activation event on the porphyrin leads to a break in one of the DNA strands. A kinetic analysis of the cleavage data revealed that cleavage rates are in the order CoTMPyP > CoTBPyP > CoTOPyP with the difference being due to different DNA affinities rather than differences in cleavage rate-constants. Based on these and earlier observations, the metalloporphyrins appear bound to a partially melted region of DNA.
182 citations
TL;DR: In this article, an improved methodology was reported for the regioselective nitration of the phenyl groups of meso-tetraphenylporphyrin 1, using NaNO2 and TFA.
175 citations
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