Exam 4: Enzymatic Reactions

Alanine transaminase is a liver enzyme important in assessment of liver function.Figure 4.12 shows the "V vs.[S]" curve for the normal enzyme (solid line) and the same enzyme in the presence of the enzyme inhibitor 2-aminobutanoic acid (dashed line). Which is true regarding the inhibitor 2-aminobutanoic acid?

Racemase enzymes interconvert:

Aldehyde groups are present in some metabolites.These aldehyde groups are most likely to be metabolized with the help of which type of enzyme?

Thiol proteases cleave peptide bonds by a mechanism similar to that of serine proteases, such as trypsin and chymotrypsin, but they contain cysteine instead of serine.In which way does the sulfhydryl group of cysteine participate in the reaction?

The maximal reaction rate (Vmₐₓ) is a kinetic property of an enzymatic reaction that depends on the incubation conditions, the enzyme concentration, and:

Most NAD-using enzymes are named as:

C.G.is a 30-year-old retired stockbroker who has developed possible skin cancer while sailing in Polynesia.A skin biopsy is analyzed for cyclin-dependent kinase activity at different concentrations of the cosubstrate adenosine triphosphate (ATP).The results are shown in Figure 4.7. The apparent effect of the drug on C.G.'s kinase activity is to:

Two different subtypes of matrix metalloproteinase, enzymes MMP-2 and MMP-9, are released from a squamous cell carcinoma.The enzymes behave according to Michaelis-Menten kinetics by the measured parameters in the table, in the same substrate: Оn the basis of these data, which of the following is a true statement?

The term ligase refers to a class of enzymes that catalyzes:

Data are plotted for the action of a histone-modifying enzyme (solid lines) in two graph formats in Figure 4.10.Dashed lines indicate the data for the enzyme in the presence of an effector molecule, deoxycytidine triphosphate (dCTP). Which statement is not true regarding this enzyme, its substrate (histone protein), and its effector dCTP?

The "catalytic triad" in the active site of the serine protease thrombin contains the three amino acids:

Neviripine is a drug for human immunodeficiency virus (HIV) infection that is a noncompetitive inhibitor of reverse transcriptase.As a noncompetitive inhibitor, it:

Which is true for enzymes in general?

A cold virus produces an enzyme rhinase, which is acted upon by a drug called rhinex.Rhinex is known to be a noncompetitive inhibitor of the viral enzyme.Which of the dashed lines in Figure 4.8 describes the action of the enzyme in the presence of drug? The solid line describes the action of the drug-free enzyme.

Which of the following is characteristic for the active sites of enzymes?

The enzyme that catalyzes the following reaction (where ADP = adenosine diphosphate) belongs to which broad enzyme class? Protein + ATP → Phosphoprotein + ADP

Tadalafil (Cialis) is a competitive inhibitor of phosphodiesterase type 5.As a competitive inhibitor, you can expect tadalafil to:

The rate of a typical enzyme-catalyzed reaction:

In which way is the transition state of an enzyme-catalyzed reaction different from the transition state of the corresponding uncatalyzed reaction?

A liver enzyme called two-substrate inactivates a drug by the following reaction, where NADP is nicotinamide adenine dinucleotide phosphate and NADPH is the reduced form of NADP: Drug + NADPH ? Inactive product + NADP⁺ The Km and physiological substrate concentrations (both in millimoles per liter) are given in the table for both substrates. What is the rate-limiting substrate under these conditions, and what is the derived Michaelis-Menten equation that describes the velocity of product formation by the enzyme?