Biochemistry Homework Assistance!

[MathFreak1990]

I'm currently doing an assignment for my biology class, and am stuck on this component of the assignment. Any assistance of any sort will be really appreciated! Any clues? Im really stuck on most of these questions and my TA or prof won't reply.

Amino Acid Sequence: MLWVFILAGHDEPFKRLFKKFARKWFDELGSPVLVFVWQGGPFKRLFKKFARKWFDELG

1. How many residues present in the sequence? How would you calculate the specific molecular mass of the protein? How would you calculate the average molecular mass of the protein?

2. Knowing about the factors that contribute to the different types of secondary structure, what will be the most likely arrangement of secondary structure elements for the amino acid sequence given? Justify this answer by providing properties of each amino acid (polar, non polar, uncharged polar).

3. Which residues in the amino acid sequence will contribute to the active site of the protein? Please explain and justify answer.

4. What type of motif does the amino acid sequence represent?

5. Find the net charge of the 59 amino acids at a pH of 7. What type of absorption chromatography would this sequence bind to at pH of 7? Please explain.

6. Is this peptide in danger of oxidation? If yes, please list the residues that are in danger. Explain your answer.

7. If this peptide were to be subjected to digestion using trypsin, what would be the resultant peptide fragment?

8. If this peptide were to be subjected to digestion using chymotrypsin, what would be the resultant peptide fragment? How would you use the tryptic and chymotryptic digests to re-esemble the full peptide sequence?

 

ATTEMPTED ANSWERS:

 

1. 59 residues in the protein, molecular mass of 7192.5 Da, and average molecular mass of 121.92 Da (7192.5 Da/59)

 

 

THANK YOU FOR ANY HELP IN ADVANCE!

[BabcockHall]

@OP 7. and 8. Do you know the specificities of trypsin or chymotrypsin? What are the chemical properties that each protease is looking for?

5. Do you know which amino acid residues have side chains that are charged? Do you know the charge on a cation exchange resin? An anion exchange resin?