You could try:

y = re.findall(r"\(\s*[a-zA-Z]+\s*\)", x)

Where x is the input.

Note – You will have to import re by using the statement import re before the program, to use the regex functions

Explanation –

re.findall is a module that returns an array of the matches found by the regex. The arguments are as follows: regex, string

r"\(\s*[a-zA-Z]+\)" specifies that the regex is a raw string given by the r at the start.
\( means an opening bracket ‘(‘
\s* means that the opening bracket may be followed by xero-or-more spaces
[a-zA-Z]+matches the letters inside (one-or-more)
\s* indicates that the text may be followed by zero-or-more spaces, and then the \) indicates the closing ‘)’

Edit 1 –

To answer your second doubt in the comments, you could try this:

z = []

for i in y:
    str = "(NN " + i[1:]
    z.append(str)

print(z)