The proton pump (cytochrome C oxidase or CCO) of aerobic organisms and reaction centers (RC) of photosynthetic organisms are masterpieces of equipments of nanometer-scale dimensions for exploitation of solar radiation and chemical energy.It is therefore extremely attractive to use nature’s “inventions” as blueprints for the construction of biomimetic systems that can fulfill specific functions desirable by mankind.The most important feature of CCO and RC is the precise arrangement of photoactive pigments,redox relays,and metal centers.In order to investigate CCO and RC mechanism,and to construct CCO and RC mimetic which are much easier to investigate than the huge CCO/RC membrane protein complex,we have developed a number of new techniques in recent years to site-specifically install fluorescent dyes,redox centers,and metal binding site in small,soluble proteins.These engineered small proteins have recapitulated important features of CCO and RC,including clean catalytic reduction of O2 and photo-induced charge separation.Further development along this road will yield more insight into how CCO and RC operates to achieve high efficiency and selectivity,and produce novel biological components for converting light energy and chemical energy into novel,desirable products,such as electricity and biofuels.