For the titration curve of this tripeptide (Glu-Cys-Arg- provided below in its fully protonated form), identify with the matching letters the first three max buffer regions, and the first three equivalence points. Then write the values of the pH for the max buffer regions and the value of the pI.    

How will the pka of Glu differ between ‘free’ tetrapeptide and tetrapeptide interacting with Lysine? Higher or lower than 4.2? Explain

Which of the following (A-C) represents a correct structure of the tripeptide Glu-Cys-Arg at pH=8.4 Reference table:

EXTRA POINTS: 10 Calculate the standard free-energy changes of the following metabolically important enzyme-catalyzed reaction at 25⁰C and pH 7.0 from the equilibrium constants given R = 8.314 J / mol·K and T= 25°C = 298K.   

Since enzymes are not rigid molecules but rather flexible proteins, which of the following may be attributed to this fact?   a.  active sites are able to conform to the shape of the substrate   b.  catalytic residues are oriented in such as way to aid in bond breakage and bond formation   c.  strain is placed upon the substrate while it binds to the enzyme   d.  near-attack conformations are achieved during formation of the transition state during an enzyme catalyzed reaction   e.  all of the above are correct

15. The catalytic mechanism below is an example of:   a.  covalent nucleophilic catalysis.   b.  covalent electrophilic catalysis.   c.  specific base catalysis.   d.  general base catalysis.   e.  low barrier hydrogen bond catalysis.  

In transforming the Michaelis-Menten equation into a straight line equation, y = mx + b, the Lineweaver-Burk double reciprocal plot, which of the following is NOT a true representation?   a.  slope = Km/Vmax   b.  y-intercept is 1/Vmax   c.  x-intercept is 1/Km   d.  y = 1/V   e.  x = 1/[S]

All of the following are correct statements about enzyme regulation EXCEPT:   a.  Enzymes can be inhibited by the products they produce.   b.  Enzymes can be inactivated by the addition of a functional group.   c.  Coenzyme and substrate availability can regulate enzyme reaction rate.   d.  The reaction rate slows as equilibrium is approached.   e.  The activity of an enzyme is covalently affected by allosteric regulators.

Base analysis of DNA shows it to have 24 mole percent of cytosine (moles per 100 moles total nucleotide). Based on this information, write below the percentages of the remaining bases (Guanine, Adenine and Thymine):

Calculate the velocity of a reaction of a substrate at 20 mM if Vmax = 100 μmol/mL‧sec and Km = 2 mM