import re
s = 'xyx - aaXY.aaAyyy-aABCaxYxxyYaaa.'
pattern = '[A-Z][a-z]+' # sequences of one uppercase followed by lowercase
for match in re.findall(pattern, s):
print('Found: {!r}'.format(match))
'''
run:
Found: 'Ayyy'
Found: 'Cax'
Found: 'Yxxy'
Found: 'Yaaa'
'''