A protein may contain several cysteins, which my pair together to form disulfide bonds as shown in the figure. If there is an even numbernof cysteins,n/2disulfide bonds can form. How many different disulfide pairing arrangements are possible?

For clarity, see attached for the question with the figure.

So I think the number of arrangements, N, would be equal to:

N=(n/2)!

Is this correct, and if not, could someone explain it to me? Thanks,

Kim