Reaction of a polypeptide with carboxypeptidase A releases Met. The polypeptide undergoes partial hydrolysis to give the following peptides. What is the sequence of the polypeptide?
1. Ser, Lys, Trp
2. Gly, His, Ala
3. Glu, Val, Ser
4. Leu, Glu, Ser
5. Met, Ala, Gly
6. Ser, Lys, Val
7. Glu, His
8. Leu, Lys, Trp
9. Lys, Ser
10. Glu, His, Val
11. Trp, Leu, Glu
12. Ala, Met

검증된 단계별 안내

Step 1: Understand the role of carboxypeptidase A. This enzyme cleaves the C-terminal amino acid of a polypeptide unless the terminal residue is Pro, Arg, or Lys. Since the reaction releases Met, this indicates that Met is the C-terminal residue of the polypeptide.

Step 2: Analyze the peptide fragments provided. These fragments are the result of partial hydrolysis, meaning the polypeptide was broken into smaller pieces. The goal is to reconstruct the original sequence by identifying overlaps between the fragments.

Step 3: Start with the fragment containing Met (Met, Ala, Gly). Since Met is the C-terminal residue, this fragment must represent the end of the polypeptide. Look for another fragment that overlaps with this sequence, such as Ala, Gly, His.

Step 4: Continue building the sequence by identifying overlaps between fragments. For example, if Gly, His, Ala overlaps with another fragment like Glu, His, then you can connect these fragments to extend the sequence.

Step 5: Verify the final sequence by ensuring all fragments are accounted for and that the sequence aligns with the rules of peptide bond formation. Additionally, confirm that the C-terminal residue is Met, as determined in Step 1.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

10m

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Polypeptide Structure

A polypeptide is a chain of amino acids linked by peptide bonds, forming the primary structure of proteins. The sequence of amino acids determines the polypeptide's properties and functions. Understanding the specific order of amino acids is crucial for predicting how the polypeptide will interact with enzymes like carboxypeptidase A.

Carboxypeptidase A Function

Carboxypeptidase A is an enzyme that catalyzes the hydrolysis of peptide bonds at the carboxyl-terminal end of polypeptides. It releases free amino acids, which can help identify the sequence of the original polypeptide. Knowing how this enzyme operates is essential for interpreting the results of the polypeptide's partial hydrolysis.

Peptide Hydrolysis

Peptide hydrolysis is the process by which peptide bonds are broken down, resulting in the formation of smaller peptides or free amino acids. This reaction is typically facilitated by enzymes and is important for protein digestion and metabolism. Understanding the products of hydrolysis helps in deducing the original polypeptide sequence from the resulting fragments.