I'm using 35S-methionine to label in vitro translation products, but due to the short half-life of the label I'm wondering whether I could substitute it with 14C-leucine. Promega and other manufacturers describe that one could use either 35S-methionine, 35S-cysteine or 14C-leucine.

Do you have you experience in using 14C-leucine in in vitro translation?

I'm running SDS- and native PAGE. How long exposure time it requires compared to 35S-methionine? I know, it depends, of course, on the number of methionines/leucines in the protein. But in general, if same amount of methionines and leucines, and suggested amount of radiolabel, does 14C-leucine require very long exposure times? My 35S-methionine exposure to phoshoscreen is good after 24h.