Synthetic molecules mimicking protein surface properties have wide applications in nanobiotechnology. This thesis describes the impact of nanoparticles on important biological events such as control of protein-protein and protein-small molecule interactions. Nanoparticles tailored with organic ligands would selectively recognize cytochrome c (Cyt c) or cytochrome c peroxidase (CCP). They inhibited proteins mutual binding. The binding affinity of nanoparticles and structural properties of both proteins was studied. Moreover, binding interface between nanoparticles and proteins was determined by hydrogen/deuterium exchange mass spectrometry. Orientation of Cyt c on the nanoparticles can be altered by combination of hydrophobics and Coulombic on the monolayer. Furthermore, nanoparticles would affect the rate of electron transfer between Cyt c and small inorganic complex molecules, indicating that monolayer of particle play a key role on protein reactivity. The hemin coordination in CCP was unaffected by nanoparticle binding, indicating that monolayer is important for recognizing proteins as well as keeping proteins in native and fully active form. The CCP reactivity with small substrates was altered by nanoparticles, indicating unconventional approach to genetics for studying protein-substrate interactions. In addition, self assembly of nanoparticles was studied using alternative Cyt c structure, indicating that loss of tertiary structure is critical for the formation of nanocomposite structures. The dependence of nanocomposite structure size to Cyt c:nanoparticle ratio and reversible formation of hybrid structures were discussed
