I'm really actually quite interested in why you need to do this. Generally speaking, when you load a string from a file, the perl interpreter doesn't get involved, so you end up with a literal @ in the string, and there's no need to escape it.

That's not to say that this isn't a valid requirement, only that, without information to the contrary, the likelihood of a real desire to escape this character is really quite low. Not zero, but still quite low.