8. An a-helix would be stabilized most by: A the presence of an Arg+ residue...

8. An a-helix would be stabilized most by:

A the presence of an Arg⁺ residue near the carboxyl terminus of the a-helix.

B the transmission of the protons of several peptide bonds throughout the a-helix.

C the presence of two Lys⁺ residues near the amino terminus of the a-helix.

D interactions between neighboring Asp^- and Glu^- residues

E interactions between two adjacent amino acid residues with large and bulky side chains.

Can you please explain why the answer is A

Thanks

Expert Solution

Ans. Correct option. A. Arginine has a basic side chain, which is positively charged at physiological pH. The carboxyl terminal has a negative charge at physiological pH.

So, the favorable ionic interaction between positively charged side chain of Arg and negatively charged carboxyl terminal stabilizes helix through mutual attraction.

Note that a-helices are primarily stabilized by H-bonds. Ionic interactions are less abundant than H-bonds.

# Option B. Incorrect. Protons do not transmit from one to another region of the peptide.

# Option C. Incorrect. Lys has a basic side chain and bear positive charge at physiological pH. Being positively charged, two lys residues repel each other.

Therefore, repulsion between the negatively charged residues destabilizes the helix.

# Option D. Incorrect. Both the Asp and Glu are acidic residues and bear negative charge at physiological pH. Because both the residues bear same negative charge, they repel each other – because same charge repel each other.

Therefore, repulsion between the negatively charged residues destabilizes the helix.

# Option E. Incorrect. Adjacently placed large and bulky side chains destabilizes the helix by causing stearic repulsion.

queen_honey_blossom answered 2 years ago

When you mutate a Gly residue that immediately follows an alpha-helix to an Ala residue, the...

When you mutate a Gly residue that immediately follows an alpha-helix to an Ala residue, the protein becomes less stable of 2.0 kcal/mol. Explain the molecular basis of this result.

Cro and cI proteins both have helix-turn-helix DNA binding domains. What effect would replacing cro’s DNA...

Cro and cI proteins both have helix-turn-helix DNA binding domains. What effect would replacing cro’s DNA binding domain with that of cI’s have on the life-cycle of lambda phage? Explain briefly

How would I use the single residue method to test for pesticides in baby food?

What would be the expected orientation of an amphipathic alpha helix occurring in a globular protein...

What would be the expected orientation of an amphipathic alpha helix occurring in a globular protein in aqueous solution? Select one: a. Hydrophilic amino acids are complementary to hydrophobic amino acids, so the hydrophilic side of the alpha helix should be facing toward the hydrophobic core of the protein. b. A soluble protein will have mostly hydrophilic amino acids in its core, so the helix will be arranged to have the hydrophilic side facing toward the core of the protein....

How would the presence of a repellent molecule influence the direction that a bacterium would move?...

How would the presence of a repellent molecule influence the direction that a bacterium would move? Explain using the various elements of the MCP-Che pathways.

Match each of the terms to the most appropriate statement .....Examples of these include the presence...

Match each of the terms to the most appropriate statement .....Examples of these include the presence of foreign bodies, rippling, compression, and scratches. ..........The microvilli-covered surface of a cell adjacent to a lumen ............The microtubule organizing center associated with mitotic spindle formation. ......Cellular projections with an internal structure of 9X2 +2 microtubules. ......Flat/tubular membranous sacs associated with Endoplasmic Reticulum and Golgi Apparatus ........Cell splitting, as occurs at the end of mitosis .........Made of three types of protein fiber; microfilaments, intermediate...

Respond to this: Starbucks has a big brand presence online. They are one of the most...

Respond to this: Starbucks has a big brand presence online. They are one of the most engaging companies throughout different social media platforms. If you are a fan of Starbucks coffee and a little bit internet savvy, then chances are you have come across at least one of Starbucks's social media platforms. It's online images and messages has stayed consistent with their brand values, which are honesty, sincerity, and connecting with their customers on a level unlike any other brand....

8) For each of the following costs incurred at Brockton Hospital, indicate whether it would most...

8) For each of the following costs incurred at Brockton Hospital, indicate whether it would most likely be a direct cost or an indirect cost of the specified cost object. (12 pts) Cost Cost Object Direct Cost/Indirect Cost Example Catered food served to patients A particular patient Direct Cost direct cost 1 Wages of pediatric nurses Pediatric department ? 2 Heating the hospital Pediatric department ? 3 Salary of the head of pediatrics A particular pediatric patient ? 4. Lab...

Look at this undecapeptide: Arg Asp Cys Glu Leu Lys Met Phe NH4+. What would each...

Look at this undecapeptide: Arg Asp Cys Glu Leu Lys Met Phe NH4+. What would each step do to the udecapeptide? Draw the final structure. a. treatement with iodoacetate that had no affect on the undecapeptide. b. treatment with 2 x 2-mercaptoethanol yielding a tripe-tide and octapeptide. c. treatment with carboxypeptidase A liberated leucine. d. treatment with cyanogen bromide yielding a methionine, a tripeptide and a heptapeptide. The question states that these amino acids are only some components of the...

would a molecule of methane be affected by the presence of an electric feild? explain your...

would a molecule of methane be affected by the presence of an electric feild? explain your answer.

Question