Thymine dissociation and dimer formation: A Raman and synchronous fluorescence spectroscopic study

Abstract

In this study, absorption, fluorescence, synchronous fluorescence, and Raman spectra of nonirradiated and ultraviolet (UV)-irradiated thymine solutions were recorded in order to detect thymine dimer formation. The thymine dimer formation, as a function of irradiation dose, was determined by Raman spectroscopy. In addition, the formation of a mutagenic (6-4) photoproduct was identified by its synchronous fluorescence spectrum. Our spectroscopic data suggest that the rate of conversion of thymine to thymine dimer decreases after 20 min of UV irradiation, owing to the formation of an equilibrium between the thymine dimers and monomers. However, the formation of the (6-4) photoproduct continued to increase with UV irradiation. In addition, the Raman spectra of nonirradiated and irradiated calf thymus DNA were recorded, and the formation of thymine dimers was detected. The spectroscopic data presented make it possible to determine the mechanism of thymine dimer formation, which is known to be responsible for the inhibition of DNA replication that causes bacteria inactivation.

Lignin Nanoparticles Deliver Novel Thymine Biomimetic Photo-Adducts with Antimelanoma Activity

“…CPD 6a was deprived of the adsorption band at 260 nm (C=C double bond), showing a λ max value of 191 nm. This value was in accordance with data previously reported for CPD bearing 2 -deoxy-ribose/phosphate [38], or in alternative, a phosphoramidide-like backbone [39]. As revealed by the 1 H-NMR analysis, 6a was isolated as a mixture of trans-sin isomer (TS) (H-6 multiplet signals at 4.40 ppm and 4.27 ppm, respectively) and cis-sin isomer (CS) (H-6 singlet signal at 4.36 ppm) in 4.0:1.0 TS/CS ratio (Scheme 3, Table 2).…”

Alkyne-Tagged Raman Probes for Local Environmental Sensing by Hydrogen–Deuterium Exchange

“…Studies of structural changes upon DNA damage have been mostly limited to in vitro examinations. 54,61,62 As alkyne-HDX of EdU is a viable approach to monitor DNA double helices, next we aimed to apply our strategy to investigate UV-induced DNA damage in native cellular environments. DNA damage induced by UV irradiation involves the formation of cyclobutene pyrimidine dimers (CPDs), in which the thymine dimer (T−T dimer) is the most common one (Figure 5a).…”

“…62 The reported change in spontaneous Raman spectra was observed (Figure S6a), confirming the dimer formation. 62 A similar UV condition was also suited for inducing T−T dimer formation in live cells, which was confirmed by immunostaining (anti-T dimer, Figure S6b,c). With the established condition, we next examined the formation of T−T dimer in EdU-labeled cellular DNA by alkyne-HDX (Figure 5b).…”

“…DNA damage inhibits DNA replication, interrupts the normal function of cells, and potentially leads to cell death. Studies of structural changes upon DNA damage have been mostly limited to in vitro examinations. ,, As alkyne-HDX of EdU is a viable approach to monitor DNA double helices, next we aimed to apply our strategy to investigate UV-induced DNA damage in native cellular environments. DNA damage induced by UV irradiation involves the formation of cyclobutene pyrimidine dimers (CPDs), in which the thymine dimer (T–T dimer) is the most common one (Figure a). − As a thymidine analogue, EdU would be a perfect reporter for interrogating the T–T dimer formation.…”

Nanomaterials‐assisted metabolic analysis toward in vitro diagnostics

“…Optical detection allows highly sensitive, cost-effective, and simple metabolite measurements, promising clinical diagnostics under various circumstances. [62,63] Further enhanced by designed nanomaterials, the optical biosensors can quantify metabolites in biospecimens at a wide dynamic range and low detection limit. The key roles nanomaterials acting in optical detection can be defined as probes with unique fluorescence resonance energy transfer (FRET) process for fluorescence spectrometry, as nanozyme with catalytic activities for visible spectrometry, and as substrates with plasmonic resonance effect for Raman spectrometry.…”