Determining Net Charge of a Peptide Video Lessons

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Concept: How to Determine the Net Charge of a Peptide

Problem: Answer the following seven questions (a through g) based upon a tripeptide sequence with the following amino acids (one-letter symbols are given):S I Da) What are the full names of the amino acids? Spelling counts, but capitalization does not. For an acidic amino acid, assume it is ionized and use the  –ate ending instead of –ic acid.S: I: D:b) What are the three-letter abbreviations for the amino acids?S: I: D:c) What is the overall charge of the most abundant tripeptide species at neutral pH (pH 7.0)?d) At physiological pH, what is the best description of the chemical properties of the side chain (R group)? (1. Hydrophobic, 2. Polar, Uncharged, 3. Negatively Charged, or 4. Positively Charged).S: I: D:e) What is the overall charge of the most abundant tripeptide species below pH 1.0?f) What is the overall charge of the most abundant tripeptide species at pH 11.5?g) What type of intermolecular force could the side chains form with water? (Note that these are interactions are with water, not with other amino acids.) A. Hydrophobic InteractionsB. Ionic InteractionsC. Hydrogen Bonds.

FREE Expert Solution

Given amino acid sequence: SID


a) S: Serine

     I: Isoleucine

    D: Aspartate

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Problem Details

Answer the following seven questions (a through g) based upon a tripeptide sequence with the following amino acids (one-letter symbols are given):

S I D

a) What are the full names of the amino acids? Spelling counts, but capitalization does not. For an acidic amino acid, assume it is ionized and use the  –ate ending instead of –ic acid.

S: 

I: 

D:

b) What are the three-letter abbreviations for the amino acids?

S: 

I: 

D:

c) What is the overall charge of the most abundant tripeptide species at neutral pH (pH 7.0)?

d) At physiological pH, what is the best description of the chemical properties of the side chain (R group)? (1. Hydrophobic, 2. Polar, Uncharged, 3. Negatively Charged, or 4. Positively Charged).

S: 

I: 

D:

e) What is the overall charge of the most abundant tripeptide species below pH 1.0?

f) What is the overall charge of the most abundant tripeptide species at pH 11.5?

g) What type of intermolecular force could the side chains form with water? (Note that these are interactions are with water, not with other amino acids.) 

A. Hydrophobic Interactions

B. Ionic Interactions

C. Hydrogen Bonds.

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