Gibbs energy of hydrolysis

If there are only three ionic forms the first three of these equations will apply if the final term is dropped from each. The student should be able to verify these equations and to write the appropriate pH functions for other cases. Since these relationships are met so often in biochemistry it is worthwhile to program a computer to evaluate the Michaelis pH functions and to apply them as needed. From Eq. 3-4 it can be seen that the reciprocal of the Michaelis pH function for a given ionic form represents the fraction of the total compound in that form and that the sum of these reciprocals for all the ionic forms is equal to one. Examples of the use of the Michaelis pH functions in this book are given in Eq. 6-50, which relates the Gibbs energy of hydrolysis of ATP to the pH, and in Eqs. 9-55 to 9-57, which de-... 

Microtubules in the long axons of nerve cells function as "rails" for the "fast transport" of proteins and other materials from the cell body down the axons. In fact, microtubules appear to be present throughout the cytoplasm of virtually all eukaryotic cells (Fig. 7-32) and also in spirochetes.311 Motion in microtubular systems depends upon motor proteins such as kinesin, which moves bound materials toward what is known as the "negative" end of the microtubule,312 dyneins which move toward the positive end.310 These motor proteins are driven by the Gibbs energy of hydrolysis of ATP or GTP and in this respect, as well as in some structural details (Chapter 19), resemble the muscle protein myosin. Dynein is present in the arms of the microtubules of cilia (Fig. 1-8) whose motion results from the sliding of the microtubules driven by the action of this protein (Chapter 19). 

Elongation factor EF-G and translocation. The third step in the elongation sequence on ribosomes (Fig. 29-12, step g) depends upon EF-G, a monomeric GTP-binding protein with a sequence homologous with that of other members of the G protein family. It apparently utilizes the Gibbs energy of hydrolysis of GTP to GDP to drive translocation of the peptidyl-tRNA from the A site to the P site (Fig. 29-12) and of the previously utilized (de-acylated) tRNA to the exit site. 

Effect of pH on the Standard Transformed Gibbs Energy of Hydrolysis of Phosphate Compounds... 

Figure 10.1 Standard transformed Gibbs energies of hydrolysis of phosphate compounds and changes in the binding of hydrogen ions as a function of pH at 298.15 K and 0.25 M ionic strength.

Table 6-6 Ionization of Acids at 25°C Gibbs Energies of Hydrolysis at 25°C... 

A discussion Is given of standard states appropriate to biochemical thermodynamics. Tabulated are Gibbs energies of hydrolysis of esters of acetic acid and related compounds, of thiol esters, amides, phosphates, and of glycolysis (and of decarboxylation). 

At pH = 7.0 and 37°C (310 K, blood temperature) the enthalpy and Gibbs energy of hydrolysis are A H = —20 kj moT and Afi = —31 kj moT , respectively. Under these conditions, the hydrolysis of 1 mol ATP (aq) results in the extraction of up to 31 k) of energy that can be used to do non-expansion work, such as the synthesis of proteins from amino acids, muscular contraction, and the activation of neuronal circuits in our brains, as we shall see in Chapter 5. If no attempt is made to extract any energy as work, then 20 kJ (in general, AH) of heat will be produced. 

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