Layered double hydroxides (LDH) intercalated with metal coordination compounds and oxometalates

The interactions of tetrakis(4-N-methylpyridyl)-porphine (H2TMpyP-4) and its copper(II), nickel(II), zinc(II), cobalt(III), iron(III), and manganese(III) derivatives with several nucleic acids have been investigated. Spectrophotometric titrations of H2TMpyP-4 and Cu(II)TMpyP-4 with the synthetic polymer poly(dG-dC) could be analyzed by a nearest-neighbor exclusion model leading to n approximately equal to two base pairs and equilibrium constants of 7.7 X 10(5) M-1 and 8.0 X 10(5) M-1, respectively. The other metal derivatives [except for the nickel(II) porphyrin] do not provide sufficiently large color changes with poly(dG-dC) to allow analysis. In contrast, all of these porphyrins interact with poly(dA-dT) and DNA. For those porphyrins investigated, the binding profiles are not adequately fit by a nearest-neighbor exclusion model but have profiles suggesting that cooperativity effects are important. Spectral and circular dichroic experiments both suggest base specificity. With calf thymus DNA, the copper(II) and nickel(II) derivatives show prominent negative circular dichroism (CD) features and large red shifts and hypochromicity of the Soret absorption band characteristic of GC specificity, as demonstrated with the synthetic polymer. The other metal derivatives show prominent positive induced visible CD features with small red shifts and hypochromicity of the absorption bands in the Soret region characteristic of AT specificity. Only the metal-free derivative has a conservative CD spectrum suggesting distribution among GC and AT sites.

Interactions of porphyrins with nucleic acids

Manganic porphyrins possess catalase activity and protect endothelial cells against hydrogen peroxide-mediated injury

Kinetic experiments have conclusively shown that electron transfer can take place over large distances (greater than 10 angstroms) through protein interiors. Current research focuses on the elucidation of the factors that determine the rates of long-range electron-transfer reactions in modified proteins and protein complexes. Factors receiving experimental and theoretical attention include the donor-acceptor distance, changes in geometry of the donor and acceptor upon electron transfer, and the thermodynamic driving force. Recent experimental work on heme proteins indicates that the electron-transfer rate falls off exponentially with donor-acceptor distance at long range. The rate is greatly enhanced in proteins in which the structural changes accompanying electron transfer are very small.

https://science.sciencemag.org/content/sci/233/4767/948.full.pdf

Long-range electron transfer in heme proteins

The synthesis of some substituted tetraarylporphyrins

Aggregation of Nickel(II), Copper(II), and Zinc(II) Derivatives of Water-Soluble Porphyrins

Solution properties of nickel(II) tetra(4-N-methylpyridyl) porphine and the influence of acetone, pyridine and imidazole

Study of the Kinetics of Reduction of an Iron(III) Porphyrin by Hexaammineruthenium(II). Estimate of the Self-Exchange Rate for a High-Spin Iron Porphyrin Complex

Aggregation of nickel(ii), copper(ii), and zinc(ii) derivatives of water-soluble porphyrins

Study of the kinetics of reduction of an iron(iii) porphyrin by hexaammineruthenium(ii). estimate of the self-exchange rate for a high-spin iron porphyrin complex

Esther G. Spiro

Papers

Aggregation of Nickel(II), Copper(II), and Zinc(II) Derivatives of Water-Soluble Porphyrins

Solution properties of nickel(II) tetra(4-N-methylpyridyl) porphine and the influence of acetone, pyridine and imidazole

Study of the Kinetics of Reduction of an Iron(III) Porphyrin by Hexaammineruthenium(II). Estimate of the Self-Exchange Rate for a High-Spin Iron Porphyrin Complex

Aggregation of nickel(ii), copper(ii), and zinc(ii) derivatives of water-soluble porphyrins

Study of the kinetics of reduction of an iron(iii) porphyrin by hexaammineruthenium(ii). estimate of the self-exchange rate for a high-spin iron porphyrin complex