Despite remarkable developments in the nanoscience, relatively little is known about the physical (electrostatic) interactions of nanoparticles with bio macromolecules. These interactions can influence the properties of both nanoparticles and the bio-macromolecules. Understanding this bio-interface is a prerequisite to utilize both nanoparticles and biomolecules for bioengineering. In this study, luminescent, water soluble CdTe quantum dots (QDs) capped with mercaptopropionic acid (MPA) were synthesized by organometallic method and then interaction between nanoparticles (QDs) and three different types of proteins (BSA, Lysozyme and Hemoglobin) were investigated by fluorescence spectroscopy at pH= 7.4. Based on fluorescence quenching results, Stern-Volmer quenching constant (K sv), binding constant (K q) and binding sites (n) for proteins were calculated. The results show that protein structure (eg, globular, metalloprotein, etc.) has a significant role in Protein-Quantum dots interactions and each type of protein influence physicochemical properties of Quantum dots differently.