Question on Python Split

[subhabangalore at gmail.com]

Dear Group,

Suppose I have a string as, 

"Project Gutenberg has 36000 free ebooks for Kindle Android iPad iPhone."

I am terming it as,

str1= "Project Gutenberg has 36000 free ebooks for Kindle Android iPad iPhone." 

I am working now with a split function,

str_words=str1.split()
so, I would get the result as,
['Project', 'Gutenberg', 'has', '36000', 'free', 'ebooks', 'for', 'Kindle', 'Android', 'iPad', 'iPhone.']

But I am looking for,

['Project Gutenberg', 'has 36000', 'free ebooks', 'for Kindle', 'Android iPad', 'iPhone']

This can be done if we assign the string as,

str1= "Project Gutenberg, has 36000, free ebooks, for Kindle, Android iPad, iPhone,"

and then assign the split statement as,

str1_word=str1.split(",")

would produce,

['Project Gutenberg', ' has 36000', ' free ebooks', ' for Kindle', ' Android iPad', ' iPhone', '']

My objective generally is achieved, but I want to convert each group here in tuple so that it can be embedded, like,

[(Project Gutenberg), (has 36000), (free ebooks), (for Kindle), ( Android iPad), (iPhone), '']

as I see if I assign it as

for i in str1_word:
       print i
       ti=tuple(i)
       print ti

I am not getting the desired result.

If I work again from tuple point, I get it as,
>>> tup1=('Project Gutenberg')
>>> tup2=('has 36000')
>>> tup3=('free ebooks')
>>> tup4=('for Kindle')
>>> tup5=('Android iPad')
>>> tup6=tup1+tup2+tup3+tup4+tup5
>>> print tup6
Project Gutenberghas 36000free ebooksfor KindleAndroid iPad

Then how may I achieve it? If any one of the learned members can kindly guide me.
Thanks in Advance,
Regards,
Subhabrata.

NB: Apology for some minor errors.