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1. What effect does carbonic anhydrase have on the equilibrium concentrations of

ID: 58988 • Letter: 1

Question

1. What effect does carbonic anhydrase have on the equilibrium concentrations of carbon

dioxide, water and carbonic acid?

I. Carbon dioxide increases

II. Carbon dioxide decreases

III. Carbonic acid increases

IV. Carbon dioxide does not change !

A. I and III B. II and IV C. I, II and III D. IV only E. None of these !!

2. Why is a peptide treated with dithiothreitol and iodoacetate prior to SDS PAGE?

a. This breaks the crosslinks in collagen

b. This oxidizes the disulfide bonds to form iodosulfoxides

c. This oxidizes tryptophan so it can be measured by UV absorbance

d. This oxidizes disulfide bonds and acetylates the resultant thiol groups

e. None of these

Explanation / Answer

1. A. Carbon dioxide and carbonic acid both increase. Carbonic anhydrase is a very fast enzyme which catalyzes this reaction very quickly. Hence carbonic anhydrase equilibrium increases. Increase of carbon dioxide also occurs.

2. E. None of these...The iodoacetate alkylates the cysteine residues not acetylates. dithiothreitol oxidizes disulfide bonds.