Kinetic stability of ATP – a proxy for habitality?!

Extremophiles thrive in hostile environments on Earth, such as hydrothermal vents on the ocean floor. These organisms developed a number of adaptations that allow them to survive in conditions of extreme temperature, up to 122 °C, and pressure, up to 125 MPa. A critical factor in their survival is the stability of adenosine triphosphate (ATP), an essential energy carrier whose hydrolysis could limit metabolic processes under extreme conditions. This remarkable adaptability of extremophiles has led to a growing interest in studying them, particularly with regard to exploring the potential for extraterrestrial life in our solar system.

In situ Raman spectroscopy, combined with a hydrothermal diamond anvil cell (HDAC) and a gas-pressurized autoclave, was used to study the hydrolysis of ATP in aqueous solutions at temperatures of 80 °C, 100 °C, and 120 °C and pressures up to 1670 MPa. The results indicated that ATP undergoes rapid hydrolysis at elevated temperatures, with rate constants of 4.34 × 10^-3 s^-1 at pH 3 and 2.91 × 10^-3 s^-1 at pH 7 at 120 °C, corresponding to half-lives of only a few minutes. An effect of pressure on ATP hydrolysis was observed, with hydrolysis rates increasing almost tenfold as pressure increased from 365 MPa to 1670 MPa at 100 °C. The influence of Na⁺, Ca²⁺ and Mg²⁺ was investigated. It was found that while Na⁺ and Ca²⁺ have a negligible effect, Mg²⁺ significantly reduces the hydrolysis rate up to 30% at 80 °C and 50% at 120 °C, thereby kinetically stabilizing ATP under extreme conditions.