'str' object has no attribute biopython

I'm working with biopython. I ask the input of an input ():

enz_name1 = input('ENZYME 1 NAME: ')
enz_name2 = input('ENZYME 2 NAME: ')

However, when I want to use input () to use the .catalyse option, like this:

    rb=RestrictionBatch()
    rb.add(enz_name1)
    rb.add(enz_name2)
    #enz_name=enz#  
print(rb.catalyse(my_seq,linear=False)) 

or even:

print (enz_name1.catalyse(my_seq, linear=False)

I have the error 'str' object has no attribute. And if I use the normal enzyme name (eg EcoRI or XmaI) it works, but not the string I get as input. Is there a way to convert these strings to the non-string form of those enzymes that are recognized by the .catalyse option?