A common and convenient way to predict the properties of a helix is to use the h

Question

A common and convenient way to predict the properties of a helix is to use the heptad repeat. In this model, two full revolutions of a helix (so, two turms in the cylinder) requires exactly 7 amino acids. The 8 amino acid side chain will be back to the starting position (see image below) 7. N-term 4 5 In this model, the N-terminal amino acid is located at position 1. The peptide backbone follows the solid line to position 2, 3,4, etc. Each position is the location of an amino acid side chain that is oriented outward. 2 3 Using the heptad repeat model, determine if each of the peptides below could be part of a peripheral membrane protein (one that is situated at the surface of a lipid bilayer) a. Serine-Valine-Alanine - Threonine -Glutamine - Leucine -Arginine - Cysteine b. Threonine -Serine -Aspartic Acid - Tryptophan - Phenylalanine - Asparagine -Leucine c. Valine -Alanine Threonine-Lysine -Leucine- Methionine -Aspartic Acid- Isoleucine

Explanation / Answer

The position of various amino acids across the polypeptide structure depends upon their structural complexity. Whereas small amino acids such as glycine, leuine, lysine etc are very easy to be accomodated across the bends and loops of the amino acid, it is very difficult for complex amino acids such as threonine, phenylalanine, proline etc to bear these positions since they have low flexibility across their structure. However, these complex amino acids do make up as essential sites for ligand interactions and hence can be easily found on the protruding site of the membrane proteins. Thus, the answers can be found as below:

a: Not a membrane protein

b: Membrane protein

c: Membrane protein

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.