Protein residues

[erby]

quick question regarding statistics for my biochem class:

i need to find degeneracy (W) for a half denatured protein of 100 residues.

Degeneracy is defined as the total number of isoenergetic possibilities.

So there are 99 bonds in a 100 residue protein. Half of them will be denatured. A denatured bond has 4 different possible orientations.

So basically you have 99 spots, so half denatured would be 49.5 of the bonds, each bond could be 1 of 4 orientations, and appear anywhere in the 99 spots. How many different combinations could there be?


ERBY [img]/images/graemlins/spade.gif[/img]

[AaronBrown]

It depends how you define things. There are C(99,49) = 5.04E28 ways to choose 49 denatured bonds out of 99. You can double that if you want to consider 50 denatured bonds as well.

For each of these combinations, there are 4^49 = 3.17E29 (or 4^50 = 1.27E30) ways to orient the denatured bonds.

If, instead the probability of each bond being denatured is 0.5, then there are 5^99 = 1.58E69 combinations.

[erby]

[ QUOTE ]
It depends how you define things. There are C(99,49) = 5.04E28 ways to choose 49 denatured bonds out of 99. You can double that if you want to consider 50 denatured bonds as well.

For each of these combinations, there are 4^49 = 3.17E29 (or 4^50 = 1.27E30) ways to orient the denatured bonds.

If, instead the probability of each bond being denatured is 0.5, then there are 5^99 = 1.58E69 combinations.

[/ QUOTE ]

Okay...so if i read it right the answer would be 4^49*C(99,49)? Since W is defined as all the possibilities of isoenergetic possibilities (orientation dependent)?

Thanks

ERBY [img]/images/graemlins/spade.gif[/img]