Kinetics and Bioenergetics Study Problems

(From Biochemistry 3033 at FIU - Kindly provided by Kelsey Downum)


 1.  Fumarase catalyzes the hydration of fumarate to L-malate.  Calculate
    k_cat, V_max and K_m for this reaction using both the M&ampM plot and the L-B plot). 
    [E] = 2 X 10^-6M, S = fumarate and the v_o of the hydration reaction 
    was measured at pH 5.7 and 25^oC:
 
     Fumarate       Rate of product formation
       (mM)              (mmol L^-1 min^-1)
 
        2.0                   2.5
        3.3                   3.1
        5.0                   3.6
       10.0                   4.2
 
2. Calculate the K_m and V_max for an enzyme-mediated reaction having the
   following [S] and V_o.  Graph the data using both M-M and L-B plots.
 
          [S] (mM)       Vo (mmol L^-1 min^-1)
 
            0.6               1.41
            0.4               1.33
            0.2               1.14
            0.1               0.88
            0.05              0.62
 
3. Westerik and Wolfenden have studied the inhibition of papain (E) 
   hydrolysis of p-nitrophenylhippurate ([S]).  They found that this
   reaction was inhibited by N-benzoylamino acetaldehyde.  Based on the
   following experimental data:
 
   a. calculate K_m for the substrate
   b. calculate V_max for the reaction at constant [E]
   c. what type of inhibition is this?
 
          [S]            V_o                  V_oi 
          (mM)      (mmol L^-1 min^-1)     (mmol L^-1 min^-1)
 
          0.71           0.2                 0.18
          0.4            0.18                0.15
          0.31           0.16                0.11
          0.098          0.12                0.07
          0.066          0.10                0.05
          0.040          0.07                0.04
 
4.  Many enzyme reactions are inhibited by the products of their 
    reactions.  Using the data given below for the inhibition of alcohol 
    dehydrogenase (E) oxidation of ethanol (S) by acetaldehyde (I), 
    determine:
    a. K_m and V_max; K_mapp & V_max app
    b. the type of inhibition observed
 
     Ethanol        V_o                  V_oi      (mM)    (mmol L^-1 min^-1)    (mmol L^-1 min^-1)
 
     100            24.9                19.2
      50            23.3                17.2
      30            21.3                14.7
      20            19.5                11.9
 
5.  Salicylate (I) inhibits the catalytic action of glutamate 
    dehydrogenase. 
    a. determine the type of inhibition by graphical analysis of the
    following data; and 
    b. calculate the K_m and V_max for the reaction
 
     [S]            V_o                  V_oi     (mM)      (umol L^-1 min^-1)    (umol L^-1 min^-1)
 
      1.5           0.21                0.08
      2.0           0.25                0.10
      3.0           0.28                0.12
      4.0           0.33                0.13
      8.0           0.44                0.16
     16.0           0.40                0.18
 
6.  From the following kinetic data, determine:
     a. the type of inhibition
     b. K_m & V_max for the reaction
 
     An I = 6 mM was used in inhibited reactions.
 
     [S]            V_o                  V_oi     (mM)      (umol L^-1 min^-1)    (umol L^-1 min^-1)
 
      2.0           139                  88
      3.0           179                 121
      4.0           213                 149
     10.0           313                 257
     15.0           370                 313

Bioenergetics
The Following Problems Should be Explored After Lecture 13

Use the information contained in the following table (free engeries of hydrolysis) to answer questions 1-3.

Compound delta G^o' (kJ/mol)

     Phosphoenolpyruvate      -63
     Carbamoyl phosphate      -53
     Acetyl phosphate         -44
     Creatine phosphate       -44
     Pyrophosphate            -34
     ATP (to ADP)             -31
     Glucose-1-PO₄            -21
     Glucose-6-PO₄            -14
     Glycerol-3-PO₄            -9

1. What is the direction of each of the following reactions when the
reactants are initially present in equimolar amounts? Use the data
given in the table.

     a. ATP + creatine <---> creatine phosphate + ADP
     b. ATP + glycerol <---> glycerol-3-PO₄
     c. ATP + pyruvate <---> phosphoenolpyruvate + ADP
     d. ATP + glucose <---> glucose-6-PO₄

2. Calculate the standard free-energy change for the isomerization of
glucose-6-PO₄ to glucose-1-PO₄.

3. Calculate the standard free-energy change for the following reaction at
25^oC: acetylphosphate + ADP <---> acetate + ATP.