Research On The Protection Of Protein Activity During Preparing Nanoliposome

To study the activity lost of protein and peptide drugs in the nano-liposome preparation process and mechanism of activity lost, in this paper, trypsin was token as a model drug, encapsulated in nano-liposome. And four protective agents were added in to prevent the protein activity lost, by detecting the changes in protein structure and molecular dynamics simulations to investigate the protective agent protection mechanism for protein activity.1 . Prepared trypsin nano-liposome by reverse evaporation, particle size was160nm, encapsulation efficiency was 47%, Zeta potential was -58mv; trypsin liposome activity loss to 37% of the original protein during prepare process, PEG can help to reserve protein activity, PEG as the best protective agent could help the activity reserved 46%.2. Investigated the secondary structural changes of trypsin in the preparation process using circular dichroism and Fourier transform infrared spectra, and investigated the tertiary structure changes using fluorescence spectroscopy. Circular dichroism data showed that in the preparation process the protein secondary structure changed, the ofα-helix content decreased from 18.7% to 13.2%,β-fold andβ-turn content increased from 15.6% and 27.0% to 20.3% and 31.9%, IR data showed the same trend. Fluorescence data show that the the whole liposome process decreased fluorescence. Four protective agents can stable the protein secondary structure, but less help with the changes in the tertiary structure loss, PEG best protection.3. The simplest protective gent, arginine and trypsin active sites were simulated molecular docking and molecular modeling using flexX docking and amber software, to study the mechanism of arginine and trypsin interact. The results showed that arginine can enter into the activity cavity of trypsin, and 7 pairs of hydrogen bonds can be formed, in theory, arginine can maintain the cavity of the three-dimensional structure of protein activity, prevent external factors change the activity cavity.The results showed that the protective agent may prevent trypsin active loss in nano-liposome prepraring process, by maintaining the secondary structure.