# Biophysics problem - amino acid dipoles

1. Jan 30, 2008

### wfu113

1. The dipole moment of a peptide bond is 3.7 Debye in water. Assuming that a hydrogen bond is essentially a dipole-dipole interaction, estimate the energy of a hydrogen bond between two peptides in water and in the interior of a protein (neglect the competing interactions with the solvent).

2. Relevant equations
$$_{}V_d_d = -2\left|\mu\right|^{}^2/D\left|r\right|^{}^3$$

3. The Debye part really confuses me. I tried plugging in 0.5 for the r value and using 1.23*10^-29 for the mu value. The D values are given as $$78.5\kappa\epsilon_{}_0$$ for water and $$3.5\kappa\epsilon_{}_0$$ for the interior of the protein. I feel like I'm almost there, but I don't quite have it. Please help! Thanks!
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution