Page 231 - Thermodynamics of Biochemical Reactions

Thernwdyanamics of Biochemical Reactions. Robert A. Alberty
Copyright 0 2003 John Wiley & Sons, Inc.
ISBN 0-471-22851-6

Chapter 1 Apparent Equilibrium Constants

1.1 Plot the fractions ri of ATP in the forms ATP4-, HATP3-, and ATP2-versus pH at 298.15 K and 0.25 M ionic strength.

1.2 Plot the average binding NHof hydrogen ions by ATP at 298.15 K and 0.25 M ionic strength as a function of pH. Show
that plotting equation 1.3-13 yields the same result as plotting 1.3-7.

1.3 Plot the average binding NHof hydrogen ions by ATP at 298.15 K and 0.25 M ionic strength as a function of pH at pMg
= 2, 3 4, 5, and 6.

1.4 Plot the average binding &,of magnesium ions by ATP at 298.15 K and 0.25 M ionic strength as a function of pMg at
pH = 3 4, 5, 6,7, 8, and 9.

1.5 Plot the average binding NHof hydrogen ions by ATP at 298.15 K and 0.25 M ionic strength versus pH and pMg. Also
plot the rate of change of NHwith pMg for comparison with Problem 1.6 to verify the reciprocity relation.

1.6 Plot the average binding &,of magnesium ions by ATP at 298.15 K and 0.25 M ionic strength versus pH and pMg
Also plot the rate of change of NMgWith pH for comparison with Problem 1.5 to verify the reciprocity relation..

1.7 Plot (a) the base 10 logarithm of the apparent equilibrium constant K and (b) -RTlnK' in kJ mol-'for ATP + H20 = ADP
+ Piversus pH and pMg at 298.15 K and 0.25 M ionic strength.

1.8 Plot the change in the binding of hydrogen ions A,. N(H+) in ATP + H2 0 = ADP + Pi versus pH and pMg at 298.15 K
and 0.25 M ionic strength.

1.9 Plot the change in the binding of magnesium ions A, N(Mg2+)in ATP + Hz 0 = ADP + Pi versus pH and pMg at 298.15
K and 0.25 M ionic strength.

1.10 Calculate the acid pKs at 298.15 K and ionic strengths of 0, 0.05, 0.10, 0.15, 0.20, and 0.25 M for all of the acids for
which data are given in the table BasicBiochemData.

1.1 1 Plot the pKs of acetate, ammonia, atp, and pyrophosphate versus ionic strength from I = 0 to I = 0.3 M at 298.15 K.
Biochemists are usually only concerned with the pHs in the pH 5 to 9 range.

1.12 (a) Calculate the acid titration curve for ATP at 298.15 K and 0.25 M ionic strength from the binding polynomial P.
(b) Integrate the calculated binding curve to obtain In P plus a constant of integration. The needed equations are
NH= (-l/ln(lO))(dlnP/dpH)
-1n (10) JNHdpH = 1nP + Const

1.13 (a) Test the differentiation of In P to obtain the equation for the binding NH of hydrogen ions by ATP at 298.15 K and
ionic strength 0.25 M in the region pH 2 to 10. (b) Test the integration of the equation for NH to obtain the equation for In P.
(c) Plot In p versus pH and NH versus pH. The equations involved are
NH = [H+]%
d[H 1
j*d[H' = 1nP + const

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