Eficiência da primeira lei da termodinâmica das proteínas de membrana: mero acaso, fortuita necessidade ou design inteligente?

quarta-feira, março 06, 2019

Thermodynamic first law efficiency of membrane proteins

Mert Gur, Mert Golcuk, Sema Zeynep Yilmaz & Elhan Taka

Received 15 Oct 2018, Accepted 29 Jan 2019, Accepted author version posted online: 06 Feb 2019, Published online: 04 Mar 2019

Source/Fonte: Nature


Proteins are nature’s biomolecular machines. Proteins, such as transporters, pumps and motors, have complex function/operating-machinery/mechanisms, comparable to the macro-scaled machines that we encounter in our daily life. These proteins, as it is for their macro-scaled counterparts, convert (part of) other/various forms of energy into work. In this study, we are performing the first law analysis on a set of proteins, including the dopamine transporter, glycine transporters I and II, glutamate transporter, sodium–potassium pump and Ca2+ ATPase. Each of these proteins operates on a thermodynamic/mechanic cycle to perform their function. In each of these cycles, they receive energy from a source, convert part of this energy into work and reject the remaining part of the energy to the environment. Conservation of energy principle was applied to the thermodynamic/mechanic cycle of each protein, and thermodynamic first law efficiency was evaluated for each cycle, which shows how much of the energy input per cycle was converted into useful work. Interestingly, calculations based on experimental data indicate that proteins can operate under a range of efficiencies, which vary based on the extracellular and intracellular ion and substrate concentrations. The lowest observed first law efficiency was 50%, which is a very high value if compared to the efficiency of the macro-scaled heat engines we encounter in our daily lives.

Communicated by Ramaswamy H. Sarma

Keywords: Thermodynamics, first law analysis, first law efficiency, biomolecular machines, proteins, neurotransmitter transporters, ATP-powered pumps

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