Complex sentence: The Cre protein was purified in 1983 and was found to be a 35,000 Da protein and it was also elucidated at this time that no high energy cofactors (such as ATP or NADPH) or accessory proteins are required for the recombinase activity of the purified protein.
Split into simpler sentences: The Cre protein was purified in 1983 and was found to be a 35,000 Da protein. It was also elucidated at this time that no high energy cofactors (such as ATP) or accessory proteins are required for the recombinase activity of the purified protein.