Determining Polypeptide Sequence #1 Use the following information to determine t
ID: 88389 • Letter: D
Question
Determining Polypeptide Sequence #1
Use the following information to determine the sequence of an decapeptide. Proteases and chemicals which break specific bonds in peptide sequences: Chymotrypsin, cuts on the C-terminal side of tyrosine, phenylalanine, and tryptophan. Trypsin, cuts on the C-terminal of lysine and arginine. Thermolysin, cuts on the N-terminal side of leucine, phenylalanine, isoleucine, and valine. Pepsin, cuts on the C-terminal of phenalaline, leucine, and glutamic acid. Cyanogen bromide, cuts on the C-terminal side of methionine Information about the amino acids in this sequence: There are two different negatively charged amino acids. Aspartic acid lies in the third position of this peptide sequence. The first amino acid in the sequence at the N-terminus end has a phenol side chain and has no charge. Serine lies adjacent to the amino acid that has a positive charge and has four carbon atoms in the side chain and serine also lies adjacent to the amino acid that is non-polar with three carbon atoms in the side chain. One of the amino acids is non-polar with one carbon atom in the side chain and has no charge. The amino acid placed at the C-terminus end of the sequence has a ring in the side chain that is also connected to the N-terminus part of the actual amino acid. Asparagine lies adjacent to the non-polar amino acid with sulfur that is included in the side chain. Experimental results with the chemicals added to the peptide sequence: A. Digestion with trypsin resulted in a tetrapeptide with no charge and a hexapeptide with a negative charge. B. Digestion with pepsin resulted in a negatively charged heptapeptide and a tripeptide that has no charge. C. Digestion with thermolysin resulted in two pentapeptides, one that has no charge and the other has a negative charge. D. Digestion with chymotrypsin resulted in a single amino acid with no charge and a nanopeptide that has a negative charge. E. Digestion with cyanogens resulted in an octapeptide that is negatively charged and a dipeptide that has no charge.Explanation / Answer
Based on the information provided in the question, the sequence of the peptide is:
Tyrosine-Alanine- Aspartic acid - Arginine - Serine - Valine - Glutamic acid - Methionine - Asparagine- Phenylalanine
Explanation:
As mentioned, the two negatively charged amino acids are Aspartic acid and glutamic acid. Aspartic acid lied in the third position, so keep it at the third position. The first amino acid must be tyrosine, as it is having phenol side chain at N-terminus and no charge. It is the arginine which has four carbon atoms in the side chain and has a positive charge, so the serine is lying adjacent to arginine. It is the valine which has 3 carbon atoms in side chain without charge. It is the phenylalanine which has a ring structure. Asparagine is kept adjacent to the nonpolar amino acid with sulfur that is included in the side chain, this must be the methionine.
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