Michaelian Karo, Padilla Norberto Santillán
Department of Nuclear Physics and Application of Radiation, Institute of Physics, UNAM, Cto. Interior de la Investigación Científica, Ciudad Universitaria, Cuidad de México, C.P. 04510, Mexico.
Faculty of Science, UNAM, Cto. Interior de la Investigación Científica, Ciudad Universitaria, Cuidad de México, C.P. 04510, Mexico.
Heliyon. 2019 Jun 18;5(6):e01902. doi: 10.1016/j.heliyon.2019.e01902. eCollection 2019 Jun.
Non-equilibrium thermodynamics is a relevant framework from within which to address formidable difficulties encountered in explaining the origin of life; from molecular synthesis and complexation, enzyme-less proliferation, to evolution (including the acquisition of homochirality and information). From within this framework we have proposed that the origin of life was the origin of the dissipative structuring of organic pigments which became the fundamental molecules of life (e.g. RNA and DNA) proliferated through autocatalytic photochemical reactions under the thermodynamic imperative of dissipating the imposed UVC solar photon flux available at the Archean surface. Here we present experimental evidence demonstrating that the absorption and dissipation of UVC light by synthetic DNA of 25 base pairs (and also natural salmon sperm DNA) over a range of temperatures, including below their melting temperature, leads to denaturing. Since denaturing is a non-trivial step on route to enzyme-less replication, our data suggest the possibility of a dissipative route to DNA replication at the origin of life. Such a dissipation-replication relation provides a simple mechanism for the early accumulation of both homochirality and information. Possible mechanisms of UVC photon-induced denaturing of DNA are discussed.
非平衡态热力学是一个相关的框架，可用于解决在解释生命起源过程中遇到的巨大困难；从分子合成与络合、无酶增殖到进化（包括获得同手性和信息）。在这个框架内，我们提出生命起源是有机色素耗散结构的起源，这些有机色素成为生命的基本分子（如RNA和DNA），它们在太古宙表面可利用的紫外线C太阳光子通量耗散的热力学要求下，通过自催化光化学反应进行增殖。在此，我们展示了实验证据，表明25个碱基对的合成DNA（以及天然鲑鱼精子DNA）在一系列温度下，包括低于其解链温度时，对紫外线C光的吸收和耗散会导致变性。由于变性是无酶复制过程中的一个重要步骤，我们的数据表明在生命起源时存在一条耗散途径实现DNA复制的可能性。这种耗散 - 复制关系为同手性和信息的早期积累提供了一个简单机制。文中还讨论了紫外线C光子诱导DNA变性的可能机制。
