Question

5.

a. In a Lineweaver-Burk plot, the y-intercept of the line of best fit is equal to _____ and the x-intercept of the line of best fit is equal to _____:

1) 1/V_max ; –1/K_m                                                                                             4) –1/K_m ; V_max

2) 1/K_m ; 1/V_max                                                                                              5) V_max ; K_m     

3) 1/V_max ; –K_m

b. All of the following statements are true about the relationships between [S], K_m, V_o, and V_max EXCEPT:

1) As [S] increases, V_o gets closer to V_max

2) V_max occurs when the enzyme is saturated with substrate

3) K_m is the [S] at which V_o = V_max/2

4) V_o is closest to V_max when [S] is less than K_m

c. When a protein needs to be degraded by the proteasome, it is covalently attached to another protein called _______. The final enzyme in the process that attaches these two proteins to one another is called _______.

1) Ubiquitin; ubiquitin ligase

2) Ubiquitin-activating enzyme; ubiquitin carrier protein                                     

3) Ubiquitin carrier protein; ubiquitin-activating enzyme                        

4) Proteasome; ubiquitin ligase

5) None of the above

d. If an enzyme has a V_max of 60 nM/sec, what is the V_o if the substrate is present at a concentration equal to 3K_m?

1) 12 nM/sec                                                                                      4) 180 nM/sec

2) 45 nM/sec                                                                                     5) Cannot be determined from information given

3) 60 nM/sec                         

e. The pH at which a protein is usually least soluble is equal to

1) 1                                                      

2) 7                                                     

3) The pH at which the protein charge is most negative

4) The isoelectric point (pI) of the protein

5) pKa of the main chain –COOH group

Answer 1