Answer the following questions with explanation. Thanks.
Answer The Following Questions With Explanation Thanks 1 (150.8 KiB) Viewed 44 times
2. (15 points) The tetrapeptide cholecystokinin-4 shown below causes the brain to feel anxiety. A) Circle the N- and C-terminus. One of them has been chemically modified. B) Write the 3-letter and 1-letter codes of the amino acids in order from N-terminus to C-terminus. C) Calculate the total charge of the peptide at pH 4.0 to two decimal places. Use the pKa values given on the last page. Show work. (The peptide is shown in an “uncharged” state—it is up to you to assign correct charges.) HN N 2 علم. پایان کابل M HN. O
6. (15 points) You need to prepare 1.000 L of a 0.875 M citrate buffer of pH 4.76, starting from citric acid (H3C6H5O7). You measure out 0.875 moles of citric acid and then add 6 M NaOH to adjust the pH before filling up the volume to 1.000 L. Answer the following questions. You must show work on part (c) to receive credit. PK1 = 3.13 2 O'S 1 Cit- PK2 = 4.76 PK3 = 6.40. (a) Which two forms of citric acid (Cit) are most prevalent at pH 4.76? (circle two): H3Cit H2Cit HCit2- (6) How many OH mole equivalents are needed to reach pH 4.76? (circle one): 3 0.5 1 1.5 2 2.5 3 (c) Using the information from (b), calculate the volume (in mL) of 6 MNOH needed to reach pH 4.76: اكره2
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