constructed a branched fusion consisting of the monooxygenase cytochrome P450, putidaredoxin (Pdx) and Pdx reductase (Pdr) in order to achieve improved electron transfer efficiency of the two redox partners, thereby accelerating the enzymatic reaction catalyzed by P450. As a result, a large increase in the initial reaction rate was obtained when compared with an equimolar mixture of the free proteins. The same group demonstrated another example of self-assembly with proliferating cell nuclear antigen (PCNA) scaffold-fused P450, Pdx and Pdr in an in vitro system ( Haga et al., 2013 and Hirakawa and Nagamune, 2010), where trimeric PCNA subunits were individually fused with the three proteins, forming a very tight and compact complex for a more efficient monooxygenase reaction.