High pressures increase α-chymotrypsin enzyme activity under perchlorate stress

Abstract

Deep subsurface environments can harbour high concentrations of dissolved ions, yet we know little about how this shapes the conditions for life. We know even less about how the combined effects of high pressure influence the way in which ions constrain the possibilities for life. One such ion is perchlorate, which is found in extreme environments on Earth and pervasively on Mars. We investigated the interactions of high pressure and high perchlorate concentrations on enzymatic activity. We demonstrate that high pressures increase α-chymotrypsin enzyme activity even in the presence of high perchlorate concentrations. Perchlorate salts were shown to shift the folded α-chymotrypsin phase space to lower temperatures and pressures. The results presented here may suggest that high pressures increase the habitability of environments under perchlorate stress. Therefore, deep subsurface environments that combine these stressors, potentially including the subsurface of Mars, may be more habitable than previously thought.

Structural responses of model biomembranes to Mars-relevant salts

“…We showed that high pressures increase a-chymotrypsin enzyme activity even in the presence of high perchlorate concentrations. 21 The results suggested that high pressures may increase the habitability of environments under perchlorate stress. In another study it has been shown that the driving force for liquid-liquid phase separation and condensate formation of proteins is strongly influenced by the type of Martian salt and its concentration.…”

“…One particular ion is perchlorate, ClO 4 À , which is found in extreme environments on Earth and ubiquitously on Mars. [19][20][21] Perchlorates are also known to act as chaotropes, perturbing the structure of water and its hydrogen bonding capacity, 22 and might hence affect biomolecular hydration, structure and function. Perchlorate salts, particularly Mg(ClO 4 ) 2 and Ca(ClO 4 ) 2 , exhibit deep eutectic temperatures allowing for the presence of liquid water at temperatures as low as À70 1C, therefore highlighting the case for their presence in subsurface Martian environments.…”

“…Previous studies have demonstrated deleterious effects of destabilizing ions such as perchlorates on the activity of a-chymotrypsin (a-CT) and other enzymes at ambient conditions. 20,21,28 Conversely, stabilizing salts, such as magnesium sulfate, MgSO 4 , have been shown to increase the activity and structural stability of a-CT. 21 In recent work, we demonstrated that high pressures increase the enzymatic activity of a-CT even in the presence of high perchlorate concentrations, and the results suggested that high hydrostatic pressures may increase the habitability of environments under perchlorate stress. Therefore, deep subsurface environments that combine these stressors, potentially including the subsurface of Mars, may be more habitable than previously thought.…”

“…Therefore, deep subsurface environments that combine these stressors, potentially including the subsurface of Mars, may be more habitable than previously thought. 21 The effects of these Martian salts on other biomolecular systems, such as the cellular membrane, is still unknown. Biological cells are surrounded by cytoplasmic membranes that function as barriers between the cytoplasm and the extracellular environment.…”

New thermodynamic activity-based approach allows predicting the feasibility of glycolysis

“…The feasibility largely depends on the composition of the reaction medium, temperature, pressure, and pH. The reason behind this multifaceted dependency is the interaction between the enzyme and the surrounding reaction medium as well as the influence of the reaction medium on the interactions of the metabolites 2 , 3 . Thus, including thermodynamic constraints to develop new processes is promising; such constraints help to evaluate that thermodynamically unfeasible routes are excluded.…”