T7 RNA polymerase inhibitor

[Yim, Harry M'bio]

Does anyone know of an EFFECTIVE inhibitor of T7 RNA polymerase?  
Specifically I am looking for something that inhibits initiation but 
not elongation.  I am studying RNA folding and so an additional requirement 
would be that it not affect RNA:RNA interactions.  I have searched in the 
literature and there doesn't seem to be anything worthwhile.  Thanks.

Harry Yim
UCLA