best version of premiere pro to run?

hi, I'm currently using a 2009 Macbook Pro (MacBookPro5,5), and I'm curious which version of Premiere would be optimal for this computer. it only has 4 GB RAM and 10.11.6 on it. I know this computer is obsolete, but, it is going to be replaced this year (I'm just not sure what to replace it with yet.) Thanks