Like alpha helices, beta sheets often have one side of the sheet facing the surf

Question

Like alpha helices, beta sheets often have one side of the sheet facing the surface of the protein and the other side facing the interior, giving rise to an amphiphilic sheet with one hydrophobic surface and one hydrophilic surface Once stabilized in a beta sheet, polypeptides cannot rotate freely around their alpha-carbons, and the regular bond geometry (see beta sheet bond model, below at the left) results in amino acid side chains sticking out from the sheet on alternate sides. That is, as you walk along a beta strand (polypeptide) in a beta sheet, each successive amino acid side chain sticks out to the opposite side from the preceding amino acid: UP-DOWN-UP-DOWN-UP-DOWN-etc From the sequences listed below, PICK THE POLYPEPTIDE SEQUENCE THAT COULD FORM A STRAND IN AN AMPHIPHILIC BETA SHEET. Look for whether the alternation of side chains facing UP or DOWN would segregate the polar and non-polar side chains. (And remember the mnemonic: "FAMILY VW") IIN N1lI I N N II NI II N Figune 3-3 MBoCi The Preblems Bk(O Gafand Scence 2015 DKLVTSIAREFM DSETKNAVFLIL TLNISFQMELD V

Explanation / Answer

Answer:
Option D is correct

Explanation:
Nonpolar amino acids = FAMILY VW

Look for the peptide sequence which has alternative polar non-polar amino acids.
T = Polar
L = Non-polar
N = Polar
I = Non-polar
S = Polar
F = Non-polar
Q = Polar
M = Non-polar
E = Polar
L = Non-polar
D = Polar
V = Non-polar

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