Formation of long-lived reactive products in blood serum under heat treatment and low-intensity laser irradiation, their role in hydrogen peroxide generation and DNA damage

214-223Long-lived reactive protein products were shown to be evolved under heat treatment and low-intensity laser irradiation in blood serum in presence of dissolved oxygen from the air. These reactive protein products generate hydrogen peroxide for a long time, which results from conjugated electron-radical chain reactions. Long-lived reactive protein species play an important role in the adaptation of living systems to stress factors. Apparently, the formation of visible light- and heat-induced reactive protein species is not specific to just blood serum proteins, rather than it could also be a feature of other proteins

Formation of long-lived reactive products in blood serum under heat treatment and low-intensity laser irradiation, their role in hydrogen peroxide generation and DNA damage

Long-lived reactive protein products were shown to be evolved under heat treatment and low-intensity laser irradiation in blood serum in presence of dissolved oxygen from the air. These reactive protein products generate hydrogen peroxide for a long time, which results from conjugated electron-radical chain reactions. Long-lived reactive protein species play an important role in the adaptation of living systems to stress factors. Apparently, the formation of visible light- and heat-induced reactive protein species is not specific to just blood serum proteins, rather than it could also be a feature of other proteins

Energetics of base flipping at a DNA mismatch site confined at the latch constriction of α-hemolysin

Unique, two-state modulating current signatures are observed when a cytosine-cytosine mismatch pair is confined at the 2.4 nm latch constriction of the [small alpha]-hemolysin ([small alpha]HL) nanopore. We have previously speculated that the modulation is due to base flipping at the mismatch site. Base flipping is a biologically significant mechanism in which a single base is rotated out of the DNA helical stack by 180[degree]. It is the mechanism by which enzymes are able to access bases for repair operations without disturbing the global structure of the helix. Here, temperature dependent ion channel recordings of individual double-stranded DNA duplexes inside [small alpha]-HL are used to derive thermodynamic ([capital Delta]H, [capital Delta]S) and kinetic (Ea) parameters for base flipping of a cytosine at an unstable cytosine-cytosine mismatch site. The measured activation energy for flipping a cytosine located at the latch of [small alpha]HL out of the helix (18 +/- 1 kcal mol-1) is comparable to that previously reported for base flipping at mismatch sites from NMR measurements and potential mean force calculations. We propose that the [small alpha]HL nanopore is a useful tool for measuring conformational changes in dsDNA at the single molecule level

Model Systems of Protein-Nucleic Recognition

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