Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 5: Problem 2

Amino acid analysis of an oligopeptide 7 residues long gave \(\begin{array}{lllll}\text { Asp } & \text { Leu } & \text { Lys } & \text { Met } & \text { Phe } & \text { Tyr }\end{array}\) The following facts were observed: a. Trypsin treatment had no apparent effect. b. The phenylthiohydantoin released by Edman degradation was c. Brief chymotrypsin treatment yielded several products, including a dipeptide and a tetrapeptide. The amino acid composition of the tetrapeptide was Leu, Lys, and Met. d. Cyanogen bromide treatment yielded a dipeptide, a tetrapeptide, and free Lys. What is the amino acid sequence of this heptapeptide?

Short Answer

Expert verified
The amino acid sequence of the heptapeptide is Phe-Tyr-Lys-Met-Leu-Lys.

Step by step solution

01

Analyzing effects of Trypsin and Chymotrypsin treatment

Nothing happened when trypsin was used, indicating that Lys is not at the carboxyl end. However, chymotrypsin treatment resulted in a dipeptide and a tetrapeptide, interestingly tetrapeptide does not contain Phe or Tyr, this means that the carboxyl end must be Phe or Tyr.
02

Observing results of Cyanogen Bromide treatment

Cyanogen bromide yielded a dipeptide, a tetrapeptide, and free Lys. There are two places where the peptide must split, before Lys and before Met, Lys cannot be at carboxyl end as indicated by step 1, so it must be the one at the N-terminus of peptide. Then the sequence before Met must be a tetrapeptide, thus the sequence after Met must be a dipeptide.
03

Observing Edman Degradation

Since Tryp is not used for the first step, it means that Lys is not the first amino acid, and the N-terminus must be Phe followed by Tyr. Given these known information, Lys, Leu, Met are the remaining amino acids in the sequence. Because of the hint from Cyanogen Bromide treatment, Met and Leu must be next to each other.
04

Finalize the sequence

Considering all the information from the above steps, it can be concluded that Leu follows Met, and Lys is at the end, as it must be at the N-terminus of peptide, here it is next to Tyr, other positions would be subjected to trypsin or CNBr treatment. Thus, the final sequence is: Phe-Tyr-Lys-Met-Leu-Lys.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Phosphoproteins are formed when a phosphate group is esterified to an - OH group of a Ser, Thr, or Tyr side chain. At typical cellular \(\mathrm{pH}\) values, this phosphate group bears two negative charges \(-\mathrm{OPO}_{3}^{2-} .\) Compare this side-chain modification to the 20 side chains of the common amino acids found in proteins and comment on the novel properties that it introduces into side-chain possibilities.

A quantitative study of the interaction of a protein with its ligand yielded the following results: Ligand concentration \(1 \quad 2 \quad 3 \quad 4 \quad 5 \quad 6 \quad 9 \quad 12\) \((m M)\) \(\nu\) (moles of ligand \(\begin{array}{lllllll}0.28 & 0.45 & 0.56 & 0.60 & 0.71 & 0.75 & 0.79 & 0.83\end{array}\) bound per mole of protein Plot a graph of [L] versus \(\nu .\) Determine \(K_{\mathrm{D}},\) the dissociation constant for the interaction between the protein and its ligand, from the graph.

Describe the synthesis of the dipeptide Lys-Ala by Merrifield's solidphase chemical method of peptide synthesis. What pitfalls might be encountered if you attempted to add a leucine residue to Lys-Ala to make a tripeptide?

Amino acid analysis of a decapeptide revealed the presence of the following products: \(\begin{array}{lllll}\mathrm{NH}_{4}^{+} & \text {Asp } & \text { Glu } & \text { Tyr } & \text { Arg } \\ \text { Met } & \text { Pro } & \text { Lys } & \text { Ser } & \text { Phe }\end{array}\) The following facts were observed: a. Neither carboxypeptidase \(A\) or \(B\) treatment of the decapeptide had any effect. b. Trypsin treatment yielded two tetrapeptides and free Lys. c. Clostripain treatment yielded a tetrapeptide and a hexapeptide. d. Cyanogen bromide treatment yielded an octapeptide and a dipeptide of sequence NP (using the one-letter codes). e. Chymotrypsin treatment yielded two tripeptides and a tetrapeptide. The N-terminal chymotryptic peptide had a net charge of -1 at neutral \(\mathrm{pH}\) and a net charge of -3 at pH 12 f. One cycle of Edman degradation gave the PTH derivative What is the amino acid sequence of this decapeptide?

Amino acid analysis of an octapeptide revealed the following composition: \(\begin{array}{llllll}\text { 2 Arg } & \text { 1 Gly } & \text { 1 Met } & \text { 1 Trp } & \text { 1 Tyr } & \text { 1 Phe } & \text { 1 Lys }\end{array}\) The following facts were observed: a. Edman degradation gave b. CNBr treatment yielded a pentapeptide and a tripeptide containing phenylalanine. c. Chymotrypsin treatment yielded a tetrapeptide containing a C-terminal indole amino acid and two dipeptides. d. Trypsin treatment yielded a tetrapeptide, a dipeptide, and free Lys and Phe. e. Clostripain yielded a pentapeptide, a dipeptide, and free Phe. What is the amino acid sequence of this octapeptide?
See all solutions

Recommended explanations on Chemistry Textbooks

Chemistry Branches

Read Explanation

Kinetics

Read Explanation

Organic Chemistry

Read Explanation

The Earths Atmosphere

Read Explanation

Inorganic Chemistry

Read Explanation

Chemical Reactions

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free