# Relationship between Interaction Energy and Melting Temperature

1. Jun 30, 2010

### sozo91

1. The problem statement, all variables and given/known data

So this is not really a homework problem, but it is an academic-related problem which I want to solve.

Suppose in my current research position, I'm making synthetic Collagen heterotrimers, composed of A,B,C monomers, which form into a triple helix arrangement. Each monomer is composed of 10 amino acid X-Y-G motifs, where X and Y are arbitrary amino acids and G is glycine.

In experiments using Circular Dichroism, we can determine the melting temperature of A,B,C heterotrimers in solution (we can also make homotrimers of A,A,A or other combinations like A,A,B).

I ask, then, are there any relevant equations relating interaction energy (relating to interactions between amino acid units in each monomer) and melting temperature?

2. Relevant equations

3. The attempt at a solution

Here I will provide more detail. In our lab, we specifically incorporated only 4 different types of amino acids, Proline (P), Hydroxyproline (O), Arginine (R) and Glutamate (E) as possible X,Y candidates. From there we constructed five distinct units based on the unit's stability and occurrence in nature: PEG,PRG,EOG,ROG,POG.

Of the five, POG is the most frequent and it has been shown (both empirically and theoretically) that adding more POG to your collagen unit significantly adds to the stability of the Collagen triple helix.

So the lab devised an equation to compute interaction energy:
$${E(AB) + E(BC) + E(CA)} - 3.8* \sum {(POG)}$$

I don't really want to go into more detail, so I'll sum up.

What I want to do is revise this to reflect the stability we find in melting temperatures.

Any help will be greatly appreciated. Thanks.