Studies on interaction between CdTe quantum dots and α-chymotrypsin by molecular spectroscopy

Abstract

In this article, the interaction between α-Chymotrypsin and CdTe QDs was investigated by fluorescence, synchronous fluorescence, and circular dichroism (CD) spectroscopic methods at pH 7·20 and pH 9·05. The intrinsic fluorescence of α-Chy is quenched by CdTe QDs. Under different pH conditions, the level of binding constants is determined to be 103 from fluorescence data. The hydrogen bond or van der Waals force is involved in the binding process when pH is 9·05, while the hydrophobic and electrostatic interactions play main role in the binding process when pH is 7·20. The red-shift of synchronous fluorescence spectral peak of protein after the addition of CdTe QDs reveals that the microenvironments around tryptophan residues are disturbed by CdTe QDs. The secondary structure of α-Chy undergoes slight changes as similar by far-UV CD data. The activity and stability of α-Chy in the presence of CdTe QDs were also studied. α-Chy can maintain its high activity and stability under different pH conditions for 24 h in the presence of CdTe QDs.