Title:Effect of Cadmium Sulfide Quantum Dots on Physical Properties of R-Phycoerythrin as a Protein Matrix
Volume: 20
Issue: 1
Author(s): O.D. Bekasova, I.V. Safenkova, P.I. Misurkin, V.A. Timofeeva and B.I. Kurganov
Affiliation:
Keywords:
Quantum dots, CdS nanoparticles, R-phycoerythrin, atomic force microscopy, flicker-noise spectroscopy, nanostructures, protein molecules, protein–protein interactions, conformational mobility, biomacromolecules
Abstract: The synthesis and analysis of nanostructures in the cavities of protein molecules is a promising research field in
the industry of nanosystems. In this study, atomic force microscopy (AFM) has been used to evaluate the properties of
CdS quantum dots synthesized in the tunnel cavities of R-phycoerythrin, a 290 kDa water-soluble pigment protein responsible
for light harvesting in red algae. It has been shown that R-phycoerythrin dissolved in deionized water to a concentration
of 50 μg/ml is prone to self-organization into regular spatial structures upon adsorption on the surface of mica, but no
such structuring takes place in films prepared from R-phycoerythrin solutions diluted tenfold. In the latter case, protein
molecules are deformed, as judged from the analysis of the surface profile. R-phycoerythrin with CdS quantum dots in
protein cavities (the concentration of the preparation was (48 μg/ml) loses the self-organization ability and is not deformed
upon adsorption on the mica surface. Analysis of AFM images by flicker-noise spectroscopy has shown that incorporation
of CdS quantum dots into R-phycoerythrin molecules provides for “smoothing” of the protein surface, with
various irregularities being leveled off. Conversely, the irregularity of the protein surface increases when R-phycoerythrin
molecules are arranged into three-dimensional branching structures. It is concluded that CdS quantum dots interfere with
protein–protein interactions and restrain the conformational mobility of the protein. The anomalously rigid structure of Rphycoerythrin
in the presence of CdS is due to its conformational rearrangements during the synthesis of quantum dot.
