4. (5 pts) Which of the following statements are correct regarding Hemoglobin (circle all that apply).

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1 Chemistry 255-Fall2o16 Mid-quarter exam 1 (75 pts) 1. (4 pts) Consider the polypeptide with the sequence: '-.r~ Pt\w ~o-- ~ Asp-Ala-Gly-Glu-Ser-Asn-Arg-Asp. a. Would this peptide strand most likely be in the core/interior o portions of a protein? b. Which amino acid(s) in the sequence could possibly form an ion pau sa t bridge? A... '" t:l ~ u L.LAl"'.fortt\ c." tc.nj J t.l'lt 'r, 11\J. ~t blu..- i... ~ /'I... ~ t,_,.; 2 (5 pts) Which of the following would occur during protein denaturation (circle all that apply)? a. Loss of primary structure. ~ Loss of secondary structure. W Loss of tertiary structure. ':.d: Loss of disulfide bonds. -~s... QLoss of a Helix structures f. Hydrolysis of peptide of Protein function. 3 (3 pts) Circle the amino acid(s) that would have a -2 charge at ph=n. Trp Arg ( ) Leu Phe 4. (5 pts) Which of the following statements are correct regarding Hemoglobin (circle all that When BPG binds to Hemoglobin the 'T' conformation of Hemoglobin is stabilized C5) Increasing the ph causes hemoglobin to bind more oxygen- Mo~ "~ Hemoglobin contains 4 'Heme' groups. ~ When Hemoglobin binds Oxygen it releases protons (H+) e) Hemoglobin the in R conformation is considered deoxyhemoglobin. Q) The presence of BPG in the blood ultimately allows for greater oxygen delivery to the cells 5 (3 pts) Which phenomena below can be described as a result of an allosteric interaction. Oxygen binding to Hemoglobin results in a shift from the T -state to the R -state b) Oxygen binding to Myoglobin reaches saturation at high 02 pressures c) Formation of a hydrophobic region in a proteins tertiary structure. d) Formation of an a BPG stabilizing the T state of Hemoglogin.

2 6 a. (3 pts) Draw the titration curve (ph vs H + ions dissociated) of Glutamic acid (Glu) when it is part of a peptide chain? The pka of the Glu side chain is ph 0 I 0.5 H+ dissociated--> 1.0 b. (2 pts) What is the effective buffering range of Glutamic acid 1J.J '3 -" 5 Answer 7-9 regarding the reaction: N2 + 3 H2-7 2 NH3 The standard free energy change AG 0 ' is kj /mol at standard conditions. 7 3 pts) Calculate the value of the equilibrium constant Keq at a temp of 298 K and an R value of J K- 1 Mole 8. (2 pts) Does the equilibrium of this reaction lie on the left (reactants) orr(ght} (products) -c/ 9. (2 pts) What is the value of AS (entropy)? Positive, :@oro? tt W\ol.Lt.u.~.f;,"'.~'Wt\ ~ 7_ ~.,U.tult.s ~IS lov'icii..t--il"uvj.

3 Answer 10- referring to the binding curve I 1.0 l A ph= 0.8- Yo l 0.2--!b " fo H " II. B p - I I I (4 pts) Which of the following statements are correct regarding binding curve A (circle all that apply) a) The curve is Hyperbolic in shape The curve is Sigmoidal in shape The shape of the curve is representative of Cooperative binding The graphs shows hemoglobin in the 'R' state at high pressures (so torr) e) The graphs shows hemoglob~n in the 'R' state at low pressures (10 torr) 11. (3 pts) For Curve A, How much oxygen is released (%) when blood travels from the arteries at a p02 = 75 torr to the Veins with a p02 = 30 torr? o -~- O 'i -: e,.$ t;o"jo ftt,\..ta~ 12. (3 pts) On the graph above the Curves (A and B) represent 2 different phs. One is a ph of 7.2 and the other 7.6. In the space provided on the graph write in the appropriate ph for each. 13. (4 pts) What happens to the Oxygen content on hemoglobin, at 75 torr, when it goes from a ph of 7.6 to How much oxygen (%) is absorbed or released?.,_,, 1. t. 0. 4\., G.1 --'b ""' ,0. ru, \.a.ta,j..tj

4 14. (4 pts) In the Hemoglobin T state an ion bridge is formed between a His residue and Asp. In the space below depict this ion bridge (you only need to show how amino acid residues hiteract-you do not need to depict the larger structure of the protein.) 15. (5 pts) Explain how the presence of C02 effects hemoglobin's ability to bind oxygen-show pertinent reaction equations. ':") ~,~ Cu ~ ~ti>... t4tl7; - II'UI~u ~ Cot, '"'CA..L vs ~c..ot,~ C.01..'"'\\J...b -= 'Z. l "- fli ~ tt)c(u$\1\~ t:lc.llh~ Co.\.\s.tl \o\b ~~ s\"'t.. to Con\ler+ 4o ~ H.L. IT, s+.. -t. ""~ ~~., rt~ o""j.. It-t t\tp'\ ----: T -.. o 1 HliJ'-l Clc.l.li~Q ~\.uft ~ -;:;:1 <i.q~nl,ln- +o+lt.. "T s~ot.c-tc(ll... no'i- 't-.<jlol 1 Ch.. ~ fis retjauj. 16. (n pts) Draw the structure of the peptide Phe-Gly-Asp-His-Tyr at ph 4. Also include: -List then-terminus and C-terminus. -Make sure the amide bonds are 'trans'. -Draw an arrow 7 to the bonds that give rise to the Torsion angles ( <1> and 'I' ) within a peptide chain -Circle any 'chiral carbons'.

5 Answer for the 2 peptide strands shown below. 17. (3 pts) The 2 peptide strands below are representative of a: (a))antiparallel p pleated sheet 'of Parallel p pleated sheet c) a-helix d) Tertia~structure 18. (3 pts) For Peptide strand 1, label which side is then terminus and C terminus. 19. (3 pts) On strand 2 circle all the a carbons c_..«-"\of "'" ~" ~..., Peptide strand 1