Queston 1:
Pyruvate is converted to acetyl CoA in a reaction catalyzed by pyruvate dehydrogenase complex. The rate of this reaction may be monitored by measurement of the absorbance of NADH at 340nm.
a) write down the complete reaction catalysed by pyruvate dehydrogenase complex
b)what class(es) of enzymes does pyruvate dehydrogenase complex belong to?
c)Identify any co factors (or co enzymes ), if any, in this reaction.
d)calculate the molar absorption coefficient for NADH given that measurement was done in 1 cm cell and that concentration of NADH was 0.005M.The absorbance was determined to be 0.670 at 340nm.
Question 2:
The activity of a glucose oxidase preparation is determined by measuring the volume of oxygen gas consumed as a fraction of time.A 10.0 mg fraction of the preparation is added to a solution containing 0.01M glucose and saturated in oxygen.After 20 min, it is determined that 10mL of oxygen was consumed (STP). What is the activity of the enzyme preparation expressed in enzyme units(µmol/min) per milligram?
Question 3:
A student in CHE2112 has been asked to analyze an enzyme and characterize it.she set up an experiment in which the velocity of the reaction was determined at different substrate concentrations. the following was her data:
Substrate concentration[s] Initial velocities,v
(mM) (mmol/min)
0.33 0.10
0.20 0.07
0.10 0.04
0.03 0.03
0.01 0.02
a) Show by drawing a graph that this is a simple Michealis-Menten type of enzyme.
b) Using an appropriate method (graph or otherwise),determine V max and Km for this enzyme.