Question 11: Deduce the sequence of the full peptide. Give the answer in single

Question

Question 11: Deduce the sequence of the full peptide.

Give the answer in single letter code with no dashes or spaces between letters.

Question 12: Based upon the amino acid analysis, how many peptide fragments would you expect upon treatment of the peptide with chymotrypsin.

Only give a number in the answer.

Question 13: Which trypsin fragment would you expect to elute last from a cation exchange chromatography column using an elution buffer with a pH = 5.5?

Use the following information to answer the remaining quiz questions: You are in a South American rain forest looking for naturally occurring peptides with potential as drugs. You have a mobile biochemistry lab with common reagents and enzymes, an amino-acid analyzer, gel-filtration and ion-exchange chromatography, and electrophoresis. You also have an Edman Sequenator, but you have contaminated one or more of your reagents, and as a result, you cannot sequence peptides longer than about 12 residues before contaminants obscure the results. While screening extracts from the ovaries of a tropical flower, you find a peptide with potential as an antiviral agent. Your analysis is below: Amino acid analysis gives the following results: AC2E3FH2lK2LM2NR2SW. Cleavage by trypsin followed by gel-filtration chromatography gives the expected 5 products, which you sequence (shown in order of emergence from column) T1 CHEMFK T2 WIMER T3 NHAK T4 CER. T5 LS Cleavage by Staph. protease followed by gel-filtration chromatography gives the expected 4 products, which you sequence (again, shown in order of emergence from column) S1 NHAKWIME S2 MFKLS S3 RCHE S4 RCE D Question 11 3 pts Deduce the sequence of the full peptide. Give the answer in single letter code with no dashes or spaces between letters.

Explanation / Answer

11. The full sequence of the peptide is

NHAKWIMERCERCHEMFKLS

12. Chymotrypsin cleaves a peptide chain after Phe, Trp or Tyr unless followed by a Pro residue. Therefore, the digestion with the chymotrypsin would yield following three peptides

NHAKW

IMERCERCHEMF

KLS

13. pI of the fragments digested with trypsin

T1- CHEMFK - 6.74

T2- WIMER - 6.00

T3- NHAK - 8.76

T4- CER - 5.99

T5- LS - 5.52

Therefore, all the peptides would have a net negative charge at pH 5.5; T3 being the highest negative and T5 is the least negative. Hence, the fragment T5 LS would elute last when eluted with a buffer with a pH 5.5.

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.