Explore BrainMass
Share

Properties of Enzymes and Catalysis

This content was STOLEN from BrainMass.com - View the original, and get the already-completed solution here!

Which of the following statements is true of enzyme catalysts?
(a) They are generally equally active on D and L isomers of a given substrate
(b) They can increase the reaction rate for a given reaction by a thousand-fold or more
(c) They can increase the equilibrium constant for a given reaction by a thousand-fold or
more.
(d) Their catalytic activity is independent of pH
(e) To be effective, they must be present at the same (equimolar) concentration as their substrate
(f) None of the above

© BrainMass Inc. brainmass.com October 25, 2018, 9:44 am ad1c9bdddf
https://brainmass.com/biology/enzyme-catalysts-and-reactions/properties-enzymes-catalysis-585040

Solution Preview

Solution:
(Please see the attached Word file for a fully formatted version of the solution.)

Which of the following statements is true of enzyme catalysts?

The correct answer is (b) They can increase the reaction rate for a given reaction by a thousand-fold or more. Scroll down for explanations of each answer option (correct or incorrect).

(a) They are generally equally active on D and L isomers of a given substrate
INCORRECT. Most ...

Solution Summary

The solution includes the answer(s) to the multiple choice collection about enzyme structure and function, along with a brief description of why each multiple option is either correct or incorrect.

$2.19
See Also This Related BrainMass Solution

Enzyme

(See attached file for full problem description with proper symbols and equations)

2. Carbonic anhydrase of erythrocytes (Mr 30,000) is among the most active of know enzymes. It catalyzes the reversible hydration of CO2:
H2O + CO2 H2CO3

which is important in the transport of CO2 from the tissues to the lungs. If 10g of pure carbonic anhydrase catalyzes the hydration of 0.30 g of CO2 in 1 min at 37oC under optimal conditions, what is the turnover number (kcat) of carbonic anhydrase (in units of min-1)?

3. The following data describe the catalysis of cleavage of peptide bonds in small peptides by the enzyme elastase.

Substrate Km (mM) kcat (s-1)
PAPAG 4.0 26
PAPAA 1.5 37
PAPAF 0.64 18

The arrow indicates the peptide bond cleaved in each case.
(a) If a mixture of these three substrates were presented to elastase with the concentration of each peptide equal to 0.5 mM, which would be digested most rapidly? Which most slowly? (Assume the elastase is present in excess.)
(b) On the basis of these data, what molecular property of an amino acid sequence appears to dictate the specificity of cleavage by elastase. Your answer should go beyond listing the presence of one or more amino acids to a conclusion as to what about the amino acid(s) is causing the specificity.

View Full Posting Details