[ccp4bb] references on application of broad specificity of enzyme

[sreetama das]

Dear All,
I have a transferase, which is showing broad specificity for both the 
substrates (nucleotides) in our organism of interest, but is highly specific in 
other organisms.
Are there any references showing the applications of (bi-substrate) proteins 
with such broad specificity towards nucleotides?
Thanking you,
regards,Sreetama