LAUSR

Detailed knowledge of the molecular interaction of protein–quantum dot (QD) association facilitates the development of new applications in nanoscience. In this work, we determined possible interactions responsible for the association of ubiquitin with two different water-soluble QDs. We used nuclear magnetic resonance (NMR) spectroscopy to identify the interaction sites of QDs in ubiquitin in a residue-specific manner. Using CdTe and InP/ZnS QDs, we monitored and compared their association with wild-type ubiquitin and also with ubiquitin-K48C. The affected residues of wild-type ubiquitin on CdTe and InP/ZnS QD binding were similar to the interacting sites of ubiquitin with other nanoparticles. Further, dimerization of ubiquitin was observed for ubiquitin-K48C at both QD surfaces. Ubiquitin-K48C could efficiently conjugate with CdTe QDs, whereas only a direct phase transfer of ubiquitin cysteine mutant resulted in the conjugation of the protein with InP/ZnS QDs. Solid-state NMR further revealed that the pr...