Partial hydrolysis of a pentapeptide yields all possible tripeptides and dipeptides. The dipeptides that are obtained upon hydrolysis are given below. The total number of tripeptides obtained that contain 'Ala' as one of the amino acids is ________ (in integer).
Val-Ala, Gln-His, Phe-Val and Ala-Gln
Determining the Pentapeptide Sequence
The partial hydrolysis of the pentapeptide yields specific dipeptides. We can use these dipeptides to determine the sequence of the pentapeptide.
- Given dipeptides: Val-Ala, Gln-His, Phe-Val, Ala-Gln.
- From Val-Ala and Ala-Gln, we infer the sequence ...-Val-Ala-Gln-...
- From Gln-His, we add His: ...-Val-Ala-Gln-His-...
- From Phe-Val, we add Phe at the beginning: Phe-Val-Ala-Gln-His.
The determined pentapeptide sequence is Phe-Val-Ala-Gln-His.
Identifying Tripeptides with Alanine
A pentapeptide (A1-A2-A3-A4-A5) yields three possible tripeptides upon partial hydrolysis: A1-A2-A3, A2-A3-A4, and A3-A4-A5.
For the sequence Phe-Val-Ala-Gln-His, the possible tripeptides are:
- Phe-Val-Ala
- Val-Ala-Gln
- Ala-Gln-His
Now, we count the tripeptides that contain the amino acid Alanine (Ala):
- Phe-Val-Ala: Contains Ala.
- Val-Ala-Gln: Contains Ala.
- Ala-Gln-His: Contains Ala.
All three derived tripeptides contain Ala.
Final Count of Tripeptides
The total number of tripeptides obtained upon hydrolysis that contain 'Ala' as one of the amino acids is 3.
Important Questions from Peptides
A tetrapeptide, made up of natural amino acids, has alanine as the N-terminal residue which is coupled to a chiral amino acid. Upon complete hydrolysis, the tetrapeptide gives glycine, alanine, phenylalanine and leucine. The number of possible sequences of the tetrapeptide is ____________
- The structure of the dipeptide Ala-Pro derived from the natural amino acids is
