[limonade]

Hi there. I had a question regarding the hydrogen bonding of beta strands when the r group of the amino acids has hydroxyl functionality. Does the oxygen on the functional group compete with the o,xygen on the carboxylic acid at all? I posted a picture with poly phenylalanine and polyserine strands. Please if anyone could clarify

[limonade]

I know the secondary structure only involves the hydrogen bonding between the carbonyl backbone and the amide group but still...?

or am i looking at this the wrong way..

[Yggdrasil]

You need to consider the three dimensional structure of the beta sheet.  If the hydrogen bonds between the peptide groups are in the plane of the sheet of paper, the side chains are pointing up and down, perpendicular to the plane of the sheet.

[Babcock_Hall]

@OP,

Yggdrasil made an important point.  If you look at a side view of an idealized beta sheet, you can see that the R groups alternate, pointing in opposite directions on each succeeding residue.  http://www.bio.miami.edu/tom/courses/protected/MCB6/ch03/3-05a.jpg

[limonade]

thank you