Chemical Forums

Specialty Chemistry Forums => Biochemistry and Chemical Biology Forum => Topic started by: groverdot on October 10, 2014, 09:28:01 PM

Title: Proteins Questions (H-bonding b/t residues and synthetic polypeptides)
Post by: groverdot on October 10, 2014, 09:28:01 PM

I'm doing an assignment and I'm really stuck on these two questions. Can someone explain them to me/help me out with the answer? I don't recall these being covered in lecture :/

1) In proteins, the hydrogen bonding responsible for the secondary structure of a protein generally takes place between backbone carbonyl oxygen atoms and amide hydrogen atoms. In contrast, the hydrogen bonding that contributes to tertiary structure generally occurs between amino acid side chains. Two serine residues are shown below, with possible hydrogen bonds shown in green. Which bonds depict the hydrogen bonding that occurs between serine residues and contributes to tertiary structure?

I put the picture of the question here: http://www.filedropper.com/screenshot2014-10-10at80341pm (Click "Download This File". It's just a screenshot, I promise :P)

2) 2) Synthetic polypeptides can assume an α-helical structure under appropriate conditions. Indicate whether polylysine and polyglutamate form an α-helix or a disordered structure at the indicated pH values.

polylysine @ pH 13
polyglutamate @ pH2
polyglutamate @ pH 7
polyglutamate @ pH 13
polylysine @ pH 2
polylysine @ pH 7

Picture of the question: http://www.filedropper.com/screenshot2014-10-10at80818pm

Thanks for any help

Title: Re: Proteins Questions (H-bonding b/t residues and synthetic polypeptides)
Post by: Babcock_Hall on October 11, 2014, 01:18:43 PM

With respect to problem 1, it seems as if you must differentiate between the main chain atoms and the side chain atoms.  This is quite straightforward.  The main chain atoms are common to all amino acid residues, whereas the side chain atom are not.

With respect to problem 2, it might be that you are supposed to read the information from the picture, but this almost seems too easy.  My suggest is that you provide your answer, and we can go from there.