Polypeptides are polymers of amino acids. Suppose that a long polypeptide chain can undergo a transition from a helical conformation to a random coil. Consider a mechanism for a helix–coil transition that begins in the middle of the chain: 

In which h and c label, respectively, an amino acid in a helical or coil part of the chain. The first conversion from h to c, also called a nucleation step, is relatively slow, so neither step may be rate determining.

(a) Set up the rate equations for this mechanism.

(b) Apply the steady-state approximation and show that, under these circumstances, the mechanism is equivalent to hhhh... ⇄ cccc...

Transcribed Image Text:

hhhh...hchh... hchh... cccc...