How does hydrophobicity affect DNA movement?

Question

I read in a book that the rate of movement of DNA molecules from negative to positive terminal in electrophoresis is affected by hydrophobicity. Can u tel me how? One more doubt : what is the direction of movement of proteins in SDS-PAGE?

Answer 1

In SDS-PAGE you have the formation of a complex between SDS and proteins so that you have anegatively charged SDS molecule for approximately every two amino acids in the protein. This means that the protein-SDS complex will have a huge negative charge that will mask any charge of the protein itself and force the protein-SDS complex to move towards the positive electrode.

I've never heard of the other thing you are mentioning. Could you expand on that? Hydrophobicity of what? DNA has a large negative charge due to its phosphate backbone and that's the reason it migrates during electrophoresis.

Answer 2

Well i can answer the second part of this question. Since Proteins are negative and contain a negative charge. When put into a SDS Page they will migrate towards the positive charge.

Heres a good look of SDS page:
http://www.bio.davidson.edu/Courses/Molbio/SDSPAGE/SDSPAGE.html