Biochem Exam 3 Liu Review

About enzyme catalysis, which of the following is NOT true?

• Enzyme catalysis leads to great enhancement of reaction rates.

• Enzymes are geometrically specific but not stereospecific.

• Some enzymes require cofactors such as nicotinamide adenine dinucleotide.

• Enzymes drop free energy of activation but not ΔG of reactions.

• All of above.

Reactant I goes through two intermediate products (II and III) to become product IV. Based on the following reaction coordinate, which is the rate limiting step?

• I to II

• II to III

• III to IV

• I to IV

Tags

NGSS.HS-PS1-4

NGSS.HS-PS1-5

Enzyme catalytic mechanisms may include_____

• acid-base catalysis.

• covalent catalysis

• metal ion catalysis.

• Preferential binding of the transition state complex

• All of above

RNAse A is a good example of ____ catalysis.

• Acid-base

• Covalent

• Metal ion

• All of above

Within the lysozyme active site, Glu35 is in a hydrophobic environment and Asp52 is in a polar environment. During the early stages of catalysis, ____.

• Glu35 is involved in general acid catalysis.

• Asp52 is involved in general acid catalysis.

• Glu35 is involved in covalent catalysis.

• Based on the local environment, Asp52 has a higher pKa than Glu35.

Like DIPF, Sarin is a nerve agent which is used as a chemical weapon. It primarily targets____.

• Lysozyme

• RNAse A

• Serine Protease

• Zymogen

• Methyl transferase

Hg, Cd, and Co ions inhibit the enzyme Urease. Based on your knowledge, this suggests that ____.

• Urease catalyzed reactions involves acid-base catalysis.

• Urease catalyzed reactions involves covalent catalysis.

• Urease catalyzed reactions involves metal ion catalysis.

• Urease catalyzed reactions involves stabilization of the transition state.

• None of above.

Among the following amino acid residues, which one is LEAST likely to carry out nucleophilic attack?

• Ser

• Cys

• His

• Asp

• Val

Many proteases are produced as longer precursors. Why would this be the case?

• Maintains a blocked or disordered active site until activated by proteolysis or cleavage of the inactive precursor

• Prevention of activation of the protease when synthesized, thus protecting the synthesizing organ

• Regulated activation of the protease when and where it is required.

• All of the above

A new serine protease was discovered that preferentially cleaves a peptide bond adjoining a negatively charged side chain. Which of the following is true?

• The specificity pocket would mimic that of chymotrypsin.

• The specificity pocket would mimic that of trypsin.

• The specificity pocket is likely lined with amino acids such as Arg and Lys.

• It likely reacts much slower than chymotrypsin.

• It likely reaction much faster than chymotrypsin.