What is the isoelectric point of the following tetrapetide that contains the amino acids represented by...

What is the isoelectric point of the following tetrapetide that contains the amino acids represented by the single letters “DREN”, such that D is at the amino-terminal end of the peptide and N is at the carboy-terminal end.

A. 3.86
B. 4.06
C. 6.53
D. 8.8
E. 12.48

Expert Solution

The polypeptide DREN can be translated to Asp-Arg-Glu-Asn.

Where:

Asp = Aspartic acid

Arg = Arginine

Glu = Glutamic acid

Asn = Asparagine

The first thing we should do when we face a problem like this is to look up for all the pka values for each aminoacid (including the one for the side chain in case the aminoacid has one). See the detailed procedure below for a table that includes these pka values for the above mentioned aminoacids.

Now that we have all those values, we should determine which of the aminoacid is located at the amino end (NH₃) and which one is located at the carboxyl end (COO). In this problem we are already given the information that Aspartic acid is at the amino end and that Asparagine is at the carboxyl end. This means that the other two aminoacids (Arginine and Glutamic acid) will only contribute with their side chains because their amino and carboxyl groups are present in the peptide bond.

So this means that Asparagine contributes with the pka of its carboxyl group and Aspartic acid contributes with the pka of its amino group. Arginine and Glutamic acid contribute with the pka of their side chains and let's not forget that aspartic acid has a side chain as well so we must consider it.

Now we have to list the values of the 5 pka mentioned above and we just simply locate the two closest ones and average them. See the detailed procedure below for more information.

So the correct answer, using significant figures, is B) 4.06

Detailed procedure:

queen_honey_blossom answered 6 months ago

Which of the following is true about amino acids with isoelectric point around pH 10? a....

Which of the following is true about amino acids with isoelectric point around pH 10? a. the side chain must be acidic b. the side chain must be basoc c.the side chain must be polar d. the side chain must be non polar e. none of these

To calculate the isoelectric point of amino acids having other ionizable functional groups, we must also...

To calculate the isoelectric point of amino acids having other ionizable functional groups, we must also take into account the pKa of the additional functional group in the side chain. For an acidic amino acid (one with an additional acidic OH group): For a basic amino acid (one with an additional basic NH group): pI = pKa ( α -COOH) + pKa (side COOH) 2 pI = pKa ( α -NH3+) + pKa (side NH) 2 Indicate which pKa values...

2. At what point do the carbon atoms of each of the following amino acids enter...

2. At what point do the carbon atoms of each of the following amino acids enter metabolic pathways for the production of energy? State citric acid cycle, etc. a. valine b. proline c. glycine

Calculate the isoelectric point of the following amino acid – You must show your work! pKa...

Calculate the isoelectric point of the following amino acid – You must show your work! pKa of the following groups α-COOH has 2.09 α-NH3 has 9.82 R group has 3.86 Aspartate

What is an amino acid? How many amino acids are there?

1)What are amino acids? Amino group, carboxyl end, what is the side chain of an amino...

1)What are amino acids? Amino group, carboxyl end, what is the side chain of an amino acid? 2)What are essential and non-essential amino acid. 3)Which are the essential amino acids? 4)Classify the amino acids based on polarity of the R group:

The 21st and 22nd amino acids found in proteins are the rare amino acids ______________ and...

The 21st and 22nd amino acids found in proteins are the rare amino acids ______________ and ______________. ________________ are nonviral genetic elements that have reverse transcriptase activity. An example of retrotransposons in the human genome is the ____ family of sequences.

\Match the following descriptions with the corresponding amino acids: This amino acid is responsible for the...

\Match the following descriptions with the corresponding amino acids: This amino acid is responsible for the strength of rhino horns and wood lignin due to the strong hydrophobic interactions between them. Subtle decreases in the serum pH lead to the protonation of this amino acid, which promotes O2 release from hemoglobin. This amino acid is the nucleophile chymotrypsin uses to attack peptide bonds. This amino acid disrupts α-helices because it makes the nearby protein backbone too flexible (and prevents proper...

Two of the facts which differentiate lipids and carbohydrates from amino acids are that, amino acids...

Two of the facts which differentiate lipids and carbohydrates from amino acids are that, amino acids can neither be stored nor excreted. true false A baby got sick a few weeks after birth and test results show that the baby had higher than normal levels of the amino acid phenylalanine. Which of the following best describes the baby's probable diagnosis? The baby has maple syrup disease The baby has PKU More lab test are needed to confirm the cause malady...

Proteins are chains of amino acids. There are twenty different types of naturally occurring amino acids,...

Proteins are chains of amino acids. There are twenty different types of naturally occurring amino acids, and all organisms must have all twenty of them in order to survive. In this project we will be discussing the amino acid leucine. What are the two possible methods that a cell may employ to be certain that it has each of the 20 amino acids? RNA is partly made of the base uracil. What are the two possible methods that a cell...

Question