UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK.
Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Street 4a, 44227, Dortmund, Germany.
Sci Rep. 2021 Aug 16;11(1):16523. doi: 10.1038/s41598-021-95997-2.
Studies of salt effects on enzyme activity have typically been conducted at standard temperatures and pressures, thus missing effects which only become apparent under non-standard conditions. Here we show that perchlorate salts, which are found pervasively on Mars, increase the activity of α-chymotrypsin at low temperatures. The low temperature activation is facilitated by a reduced enthalpy of activation owing to the destabilising effects of perchlorate salts. By destabilising α-chymotrypsin, the perchlorate salts also cause an increasingly negative entropy of activation, which drives the reduction of enzyme activity at higher temperatures. We have also shown that α-chymotrypsin activity appears to exhibit an altered pressure response at low temperatures while also maintaining stability at high pressures and sub-zero temperatures. As the effects of perchlorate salts on the thermodynamics of α-chymotrypsin's activity closely resemble those of psychrophilic adaptations, it suggests that the presence of chaotropic molecules may be beneficial to life operating in low temperature environments.
研究盐对酶活性的影响通常是在标准温度和压力下进行的，因此错过了只有在非标准条件下才会显现的影响。在这里，我们表明，高氯酸盐盐在火星上广泛存在，会增加α-糜蛋白酶在低温下的活性。由于高氯酸盐盐的去稳定化作用，较低的活化焓有助于低温激活。通过去稳定化α-糜蛋白酶，高氯酸盐盐还导致越来越负的活化熵，这促使酶活性在较高温度下降低。我们还表明，α-糜蛋白酶的活性似乎在低温下表现出改变的压力响应，同时在高压和零下温度下保持稳定性。由于高氯酸盐盐对α-糜蛋白酶活性的热力学影响与嗜冷适应的影响非常相似，这表明在低温环境中，亲混乱分子的存在可能对生命活动有益。
