460Ex1BANS_SS07 - WRITE YOUR NAME AND I.D. NUMBER LEGIBLY...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
WRITE YOUR NAME AND I.D. NUMBER LEGIBLY ON EVERY PAGE – PAGES WILL BE SEPARATED FOR GRADING! CHECK TO BE SURE YOU HAVE 6 PAGES , NAME (print): ANSWERS INCLUDING COVER PAGE. 5-digit course ID # I swear/affirm that I have neither given nor received any assistance with this exam. Signature: Date: BIOCHEMISTRY 460 FIRST HOUR EXAMINATION FORM B (white) ANSWER KEY May 30, 2007 A NON-PROGRAMMABLE CALCULATOR MAY BE USED ON THIS EXAM. No programmable calculators are permitted, and no sharing of calculators. We have a couple of spare calculators to lend in an emergency. SHOW YOUR WORK FOR ALL CALCULATIONS , AND BE SURE TO STATE UNITS OF ANY NUMERICAL ANSWERS. If the reasoning, calculations, or answer are shown anywhere other than in the space provided, make a note in the space provided and put answer on BACK OF SAME PAGE so the grader for that page will have it. USEFUL CONSTANTS : R (gas constant) = 8.315 J •mol –1 •Kelvin –1 = 8.315 x 10 –3 kJ •mol –1 •Kelvin –1 If temperature = 25 °C, absolute temperature T = 298 K (Assume this temperature unless problem states otherwise.) Use these “generic” pK a values only when no precise pK a for a specific group is given. Ionizable group in peptides and proteins Approximate ("generic") pK a (from Berg, Tymoczko & Stryer, Biochemistry , 6th ed., 2007) Potentially Useful Equations Δ G' = Δ H' T Δ S' Δ G' = Δ G°' + RTln(mass action ratio) α -carboxyl 3.1 side chain carboxyl 4.1 imidazole 6.0 α -amino 8.0 thiol 8.3 aromatic hydroxyl 10.9 ε -amino 10.8 guanidino 12.5 Michaelis-Menten Equation: V o = V max [S] [S]+K m
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Biochemistry 460, Exam #1 Form B ANSWERS NAME May 30, 2007 Last 4 digits of SID: ___________________ page 2 1. (10 pts) Suppose that the standard free energy change for the folding of the water-soluble globular enzyme below has been measured (298K): Δ G°' folding = – 25 kJ/mol unfolded protein folded protein A. (4 pts) What is the ratio of [folded] / [unfolded] protein in solution at equilibrium? (Show work.) ratio of [folded] / [unfolded] protein at equilibrium = K eq Δ G°' folding = –25 kJ/mol = – RTlnK eq = – (8.315 x 10 –3 kJ •mol –1 •K –1 )(298 K) lnK eq K eq = e Δ G°' folding / RT = e – (–25 kJ/mol) / 2.479 kJ/mol = e +10. 1 = 2.4 x 10 4 (unitless) B. (3 pts) Starting under standard conditions, would the net reaction proceed toward the left (unfolding direction) or toward the right (folding direction)? 1) toward the left (unfolding direction) *2) toward the right (folding direction) Briefly EXPLAIN your answer on the basis of the information given above (no credit for choice without appropriate explanation). Δ
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 6

460Ex1BANS_SS07 - WRITE YOUR NAME AND I.D. NUMBER LEGIBLY...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online