Difference in preferred amino acids for parallel vs. antiparallel beta sheets

[./Jack]

Hello everybody,

I'm doing my biochemistry exam review and I stumbled upon a few questions, I can't find anything about on google.
The question is:

Quote

The diagram in Figure 1 shows the alignment of the amino acid sequences of two small proteins 30 and 22 amino acids long [...]. In the protein without the gap this region would most likely be:

A. An antiparallel β-sheet.
B. Two turns of α-helix.
C. A parallel β-sheet.
D. A β (reverse) turn.

Now, the correct answer was B, because the given sequence contained a lot of the MALEK amino acids, which are preferred in an alpha helix structure. However, because of answer A and B, I was wondering if there is a way to tell if a sequence will be a parallel or anti-parallel beta sheet based on the contained amino acids. I know that beta sheets contain a lot of FIVTYW amino acids, but I can't find anywhere if there's a difference in parallel vs. anti-parallel.

 

Thank you for your time

Jack

[Vmedvil]

3 hours ago, ./Jack said:

Hello everybody,

I'm doing my biochemistry exam review and I stumbled upon a few questions, I can't find anything about on google.
The question is:

Now, the correct answer was B, because the given sequence contained a lot of the MALEK amino acids, which are preferred in an alpha helix structure. However, because of answer A and B, I was wondering if there is a way to tell if a sequence will be a parallel or anti-parallel beta sheet based on the contained amino acids. I know that beta sheets contain a lot of FIVTYW amino acids, but I can't find anywhere if there's a difference in parallel vs. anti-parallel.

 

Thank you for your time

Jack

the difference would be FIVTYW VS WYTVIF , just like a chirality, but like 3' 5' vs 5' 3' would not be which should make sense, not actually being chiral being flipped but with a different structure. 

Edited November 13, 2017 by Vmedvil

[BabcockHall]

Answers A and C are not terribly likely as the question is written.  Beyond that, I am not aware of a difference in amino acid content between parallel and antiparallel beta strands.  The structure of DNA is not related to this question.

[Vmedvil]

1 hour ago, BabcockHall said:

Answers A and C are not terribly likely as the question is written.  Beyond that, I am not aware of a difference in amino acid content between parallel and antiparallel beta strands.  The structure of DNA is not related to this question.

Base pairs are to DNA just as Amino acids are to proteins, it is very much the same.