Circle one structure 1 structure 2 neither they

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Unformatted text preview: es for both structures. N H N H N H O O 6b) [3 pts] On the diagram, draw a O O H N single arrow clearly pointing to V L L D any one bond corresponding to the H N H N H N O dihedral angle psi. O O O N H Q K K 6c) [4 pts] What type of structures L are these? Hint: give two different N H N H N H O answers. O O O N H F I I R Structure 1 = H H H O antiparallel beta sheet Structure 2 = structure 2 structure 1 parallel beta sheet 6d) [6 pts] Suppose that sequence A is I ­K ­L ­S ­V ­E and sequence B is F ­Q ­V ­D ­L ­R. Which of the two structures, as drawn, would be amphipathic? Circle one choice below. Evaluate for each whole structure, not for the individual sequences. Feel free to draw 1 letter codes on the diagram. Structure 1 Structure 2 Both Neither Only structure 2 has all hydrophobic side chains facing same direction (above or below) 6e) [3 pts] In terms of the donor ­hydrogen ­acceptor angle, which appears to have better hydrogen bond geometry? Circle one. Structure 1 Structure 2 Neither, they are equally good It is 180 degree angle 6f) [4 pts] Draw six dots on the diagram at right to indicate the approximate appearance of a Ramachandran plot for sequence A in structure 1. Assume the angles are fairly close to theoretical values. Group of dots somewhere near  139, +135 /22 Name: ______________ KEY_______________________________________ 5 7. [6 pts] What do the side chains of Tyr, Cys and His have in common that other ionizable side chains do not? There are two possible answers ­ ­give either one. Answer in twenty words or less. They are all predominantly neutral at physiological pH The pKa values are also closer to neutral pH (His 6.5, Cys 8.5, Tyr 10.0), though Lys would be as close to neutral pH as Tyr (10.0) according to the chart on p. 1. But Tyr is a little lower according to the powerpoint notes. 8. [8 pts] Answer the following questions about weak noncovalent interactions. 8a) (2 pts) Which type of weak noncovalent interaction occurs between any two atoms nearby each other? Van der Waals interaction or London dispersion forces 8b ­d) (6 pts) Which of the other types of weak noncovalent interaction is shown in each picture below? type of interaction shown? 8b....
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This test prep was uploaded on 02/25/2014 for the course BIOC 462A taught by Professor Ziegler,baldwin during the Spring '08 term at University of Arizona- Tucson.

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