Apparent Equilibrium Constants for

The component reactions in eqn. (2) are very fast, and the system exists in equilibrium. Additional carbon dioxide entering the sea is thus quickly converted into anions, distributing carbon atoms between the dissolved gas phase, carbonate and bicarbonate ions. This storage capacity is clear when the apparent equilibrium constants for the two reactions in eqn. (2) are examined, namely... 

The role of biocatalysis in two-phase systems has many parallels with the subject we have covered under extractive reactions. It appears that a two-phase system was originally considered for transformations of water insoluble substances like steroids. Now, a series of treatises are available which teach us that the maximum value of the apparent equilibrium constant for a second-order reaction in a two-phase system can exceed the equilibrium... 

Whenever reporting equilibrium constants, detailed information concerning the reaction conditions should always be indicated. Alberty has also presented an important review of biochemical thermodynamics in which he discusses the apparent equilibrium constant for biochemical reactions (K ) in terms of sums of reactant species. 

The now classical example is lactate dehydrogenase. Sil-verstein and Boyer were the first to determine the rates of exchange between cognate pairs of reactants ie., lactate and pyruvate as well as NAD and NADH). Convenient [NADH]/[NAD ] and [pyruvate]/[lactate] ratios were chosen such that when combined they satisfied the apparent equilibrium constant for the LDH reaction. These investigators first established that each exchange rate was directly proportional to the duration of exchange and likewise directly proportional to enzyme concentration. As an additional control, they also demonstrated the equality of the pyruvate lactate exchange... 

The apparent equilibrium constants for two different carboxylic surface sites are written as... 

Figure 1.9 Plot of the base 10 logarithm of the apparent equilibrium constant for the hydrolysis of ATP to ADP and Pf at 298.15 K and 0.25 M ionic strength (see Problem 1.7).

K and went on to calculate A,G ° and AfH ° at pH 7 and ionic strength 0.25 M for the corresponding reactants. This made it possible to calculate apparent equilibrium constants for six biochemical reactions at 283.15 and... 

Table 4.5 gives the corresponding apparent equilibrium constants for the reactions in glycolysis. 

Table 4.11 Apparent Equilibrium Constants for Pyruvate Dehydrogenase, the Citric Acid Cycle, and Net Reactions at 298.15 K and 0.25 M Ionic Strength...

The values of ArG"°(TotT) in Table 7.1 and AfG"°(TotD) in Table 7.2 make it possible to calculate the apparent equilibrium constant for the reaction... 

Since tables of standard apparent reduction potentials and standard transformed Gibbs energies of formation contain the same basic information, there is a question as to whether this chapter is really needed. However, the consideration of standard apparent reduction potentials provides a more global view of the driving forces in redox reactions. There are two contributions to the apparent equilibrium constant for a biochemical redox reaction, namely the standard apparent reduction potentials of the two half-reactions. Therefore it is of interest to compare the standard apparent reduction potentials of various half reactions. 

The apparent equilibrium constant for a biochemical reaction (like equation 9.1-1) at specified pH can be calculated using... 

Source From R. A. Alberty, Arch. Biochem. Biophys. 389, 94 109 (2001). Copyright Academic Press. Note The apparent equilibrium constants for these reactions do not depend on ionic strength because the equilibrium constants for the chemical reference reactions and acid dissociation do not depend on ionic strength. 

It may seem strange not to show H+ as a reactant, but [H+] is not involved in the expression for the apparent equilibrium constant for reaction 9.5-4 because it is held constant. 

This calculation can be verified by using the data on coA and acetylcoA to calculate the apparent equilibrium constant for this reaction at the experimental conditions. 

It is more convenient to use equcalcrx because it takes a stoichiometric number matrix and a vector of the apparent equilibrium constants for a set of independent reactions in the system. Note that this program calculates a consevation matrix that is consistent with the stoichiometric number matrix, and uses it in equcalc. The transposed stoichiometric number matrix nt for the reactin without H2 O is given by... 

Calculate the apparent equilibrium constant for the net reaction for the first five reactions of glycolyis that is, reactions 6.6-1 to 6.6-5) using equation 6.1-6. Check this by simply using the net reaction. 

What is the value of for the complexation of the fourth Cl- by Pt(II) (the apparent equilibrium constant for the reverse of the reaction as written above) at 0.3 ionic strength ... 

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