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Unformatted text preview: ollowing questions. Write “D” if there is not enough information provided
to answer the question. (i) Which protein is expected to elute first when the sample is applied
to a size exclusion column? Answer: ________ (ii) Which protein has the highest pHI (pI) value? Answer: ________ (c) The slope of a semi log graph relating polypeptide molecular mass to distance of migration during SDSPAGE is -0.5 cm-1. If a polypeptide with a moelcular mass of 20,000 Daltons migrates 3.4 cm, how far does
a polypeptide with a molecular mass of 9,000 Daltons migrate in the same gel? 11 Question #11 (16 points)
This is the enzyme mechanism that WILL BE examined on the actual, real BIOL201 Midterm
Exam-I to be held on Feb. 1o, 2010 @ 7:00 PM.
BIOL 201 TAs have been instructed NOT to answer questions about this mechanism!
NOTE! READ the instructions at the bottom of the page. For full credit
you need to draw molecular structures to illustrate you answer. The following diagram shows a mechanism for the enzyme-catalyzed hydrolysis of an amide (linkage) in the
dipeptide substrate R1-R2. “His-X” and “Glu-Y” are two residues in the active site of the enzyme. The thick
arrow indicates a tetrahedral intermediate resembling the two transition states for the reaction.
His-X Glu-Y Answer the two questions on p.12 about how the enzyme increases the rate at which the peptide linkages are
hydrolyzed in aqueous solution. For full credit, it WILL BE necessary to draw some relevent molecular
structures to illustrate your answers. See next page. 12 (a) Explain....................................... (8 points: 4 points for explanation, 2 points each for 2 structures) (b)Explain....................................... (8 points: 4 points for explanation, 2 points each for 2 structures)...
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- Winter '13