jaibik bro, program ranking does play role on where you'll end up as a post doc. but the kind of research you do is more important than which school you go to. best path to follow is to read papers published (in reputed journals of course!) in the field of your research interest, find who did that research and apply to those schools. if you contact the person (he/she is very likely to be a professor) and state your interest, they might even encourage you to apply to the institution they're in which is a big plus because when you state the professor's name on your essay, that'll add more weight to your application. science is all about building networks.
summary: hunt for those schools that have better biochemistry programs/better biochemist faculties and apply to them. googling for schools with biochem program ranking might pop up some good results.