Adenosine triphosphate biological functions

In addition to their role in the formation of DNA and RNA (see Section 27.2), nucleotides have other important biological functions. For example, adenosine triphosphate (ATP) is an important energy carrier in biochemical reactions, and nicotinamide adenine dinucleotide is a coenzyme that is often involved in biochemical oxidation-reduction reactions. 

Biologically, adenosine triphosphate (ATP), the free energy of life processes, is itself an anion, bound by enzymes in order to perform its many metabolic functions. Deoxyribonucleic acid (DNA) is also a polyanion, its binding by proteins being of great importance in transcription and translation processes. Anion-binding biomimicry could therefore yield much information about fundamental biological processes. 

Second, some molecules have special biological functions. For example, the nucleotide adenosine triphosphate (ATP) serves as a cellular reservoir of chemical energy. Finally, many small organic molecules are involved in complex reaction pathways. Examples of each class are described in the next four sections. 

In this chapter we briefly note the improbability of a protein comprised of 20 different amino acids in specified sequence. Then we step through the details whereby a protein of specified sequence comes into being, and, like the accountant, sum up the cost in terms of the biological energy currency, adenosine triphosphate (ATP), that is, in terms of the number of ATP molecules consumed in the production of a protein of unique sequence. Such an essentially ordinary exercise requires inclusion in this book in order to remove unnecessary mystery of protein production, to provide an example whereby molecular machines utilize energy to produce biological structure, and to place in perspective the ease with which new protein-based machines evolve when functioning by the consilient mechanism. 

Death is the ultimate manifestation of excursion excess into the realm of insolubility. ATP Adenosine Triphosphate (ATP), the universal biological energy currency, is the ultimate solubilizer of protein. In our view, the negative hypercharged phosphate functions as a super-carboxylate to destroy hydrophobic hydration in the process of satisfying its own thirst for hydration. Thus, as paired associated hydrophobic surfaces undergo an opening fluctuation, hydrophobic hydration that would form is immediately recruited for hydration of added phosphate. As substantial hydrophobic hydration is required for the positive (-TAS) to dominate and to result in insolubility, the result of phosphorylation is solubility. In this way bound phosphate provides for protein solubilization by separation of hydrophobicaUy associated domains. 

Thermodynamic Data Jor the Hydrolysis of Adenosine Triphosphate as a Function of pH, Mg Ion Concentration, and Ionic Strength Journal of Biological Chemistry 244. 3330 (1969)... 

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