can anyone help me with my biochem homework on amino acids? 6. T or FAt a pH gre

Question

can anyone help me with my biochem homework on amino acids?

6. T or FAt a pH greater than the isoelectric point, proteins have a net negative charge. 0 0 O H H Give 3-letter abbreviated names for amino acids contained in this tripeptide. Note that the positions of the terminals are not conventional. 7. Coo HN 8. If pKr of HIS is 6.00, GLU is 4.25, and ASP is 3.65; calculate the charge on the following tripeptide at pH 3.0. For full credit, show correct charges on the peptide. The pKi for ASP is 1.88 and pK for HIS is HIS - GLU - ASP

Explanation / Answer

6. True. At low concentrations of hydrogen ion or at high pH, the amino group loses its proton and becomes uncharged, thus the overall charge in amino acid molecule is negative.

7. GLU

8. We can write it in this way : NH3-HIS-GLU-ASP-COOH

For N-terminus, if pH is greater than pK then net charge will be 0 whereas if pH less than pK then net charge will be +1

For C- terminus, if pH greater than pK then net charge is -1 and if pH less than pK then net charge will be 0

N-terminus pKa will be by default 9 and c-terminus will be 3.5

Total net charge - +1

Groups Net charge NH3 +1 HIS +1 GLU 0 ASP -1 COOH 0

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