Correct RegExp for Substituting "(word 1)(word 2)(word ...)" by "`(word 1)(word2)(word ...)"'?

[Peter Heidrich]

Dear Emacs Users,

I still have not found the right search and replace terms in order to 
substitute a set of words starting and ending with quotes.

The text is standard ASCII, encoding is iso-latin1.

Does someone have the correct terms for the search and the substitute 
regexp?

Regards,
Peter.