The following questions are about 4DXH Horse liver alcohol dehydrogenase complex

Question

The following questions are about 4DXH Horse liver alcohol dehydrogenase complexed with NAD+ and 2,2,2-trifluoroethanol.

To help you answer the questions use the links provided below for the Protein Database entry information about (4DXH) , and the BRENDA database website:

http://www.rcsb.org/pdb/explore/explore.do?structureId=4DXH

http://www.brenda-enzymes.org/

Q1) The subunit-subunit interface is comprised of sandwich-like structure that is a/n __________ with a ____________.

1. parallel beta sheet; nonpolar interior

2. parallel beta sheet; polar interior

3. antiparallel beta sheet; nonpolar interior

4. antiparallel beta sheet; polar interior

Q2) Semi-opaque surface renderings of 4DXH indicate that _________ is/are fully buried in the binding site, while the bound ______ extend/s to the surface of the protein.

1. zinc; 2,2,2-trifluoroethanol and NAD+

2. 2,2,2-trifluoroethanol and zinc; NAD+

3. 2,2,2-trifluoroethanol and NAD+; zinc

4. zinc and NAD+; 2,2,2-trifluoroethanol

Q3) The specific binding of NAD+ to this enzyme is afforded by which of the following interactions?

1. Multiple hydrogen bonds

2. Multiple hydrophobic interactions

3. Multiple bridged hydrogen bonds

4. All of these interactions contribute to the specificity.

Q4) In the BRENDA database, what is the apparent trend between pH and Km when ethanol is used as a substrate for horse liver alcohol dehydrogenase (ignore all entries with no pH data, values obtained at 37 degreesC, and values obtained from mutant enzymes)?

1. Between pH 6 and 10, there is no change in Km.

2. Between pH 6 and 10, Km goes down as pH goes up.

3. Between pH 6 and 10, Km goes up as pH goes up.

Q5) What is the highest reported kcat for ethanol oxidation by horse liver alcohol dehydrogenase in the BRENDA database?

1. 29.6 s-1

2. 56.6 s-1

3. 308 s-1

4. 3500 s-1

Explanation / Answer

1)

2)

3)

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