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Unformatted text preview: 1 BIS 102 Name ____________ Key _________________________ Fall, 2002 Last First K. Hilt Second Midterm Score (100): ___________ 1. ( 5 pts.) Interpreting the results of an N-terminal protein labeling experiment is not always easy. Assuming that you performed the labeling steps correctly, give two explanations for why you might get two different N-termini? 1. More than one protein present. 2. 4 o structure still present. First correct answer (+3) 2. ( 5 pts.) BPG is not used in the red blood cells of all organisms. Other compounds can be used. Do you think an organism might use lysine, glucose, or ATP in place of BPG? Explain. ATP (+1). Organism needs a small molecule with a net negative charge (+4) at physiological pH. ATP is the only compound, of the three, that satisfies the latter. 3. Dr. Sanger incubated a peptide fragment of insulin with excess amounts of 1-fluoro-2,4- dinitrobenzene. ( 5 pts.) a) At what pH (approximately) did he carry out this incubation? Why did he choose this pH, instead of one much higher or lower? Explain. PH 8 (+1). At this pH, a significant proportion of the N-terminal α-NH2 group will be in the base form, capable of attacking the FDNB. A lower pH will diminish the proportion of the base form (+2). A higher pH will increase the likelihood of dinitrophenol being produced (+2). (+2)....
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This note was uploaded on 10/07/2009 for the course BIS 52192 taught by Professor Enochbaldwin during the Fall '09 term at UC Davis.
- Fall '09