Understanding How a New Hachimoji Nucleobase Alters Photodynamics of Genetic Building Blocks^†

Area of Science:

• Photochemistry and Photobiology
• Biophysics
• Astrobiology

Background:

• The search for alternative nucleobases is crucial for understanding the origins of life.
• 5-aza-7-deazaguanine (5N7C G) has been proposed as a potential alternative to canonical nucleobases.
• Understanding the photostability of nucleobases is essential for their potential roles in early Earth environments.

Purpose of the Study:

• To investigate the excited state dynamics and photostability of 5-aza-7-deazaguanine (5N7C G).
• To compare the photophysical properties of 5N7C G with those of guanine.

Main Methods:

• Ultraviolet (UV) absorption spectroscopy.
• Fluorescence quantum yield measurements.
• Excited state lifetime analysis.

Main Results:

• 5N7C G exhibits slower decay from its excited state compared to guanine.
• The fluorescence quantum yield of 5N7C G is greater than that of guanine.
• 5N7C G demonstrates reduced UV photostability relative to guanine.

Conclusions:

• The reduced UV photostability of 5N7C G suggests it may have faced disadvantages in prebiotic conditions.
• These findings have implications for the evolution of genetic material and the search for extraterrestrial life.
• The photophysical properties of alternative nucleobases are critical for assessing their potential biological relevance.