Autosampling systems
The HTCD allows automated scanning measurements using pre-programmed parameters. The autosampler can be set to maintain the microplate rack or vial rack at a constant temperature to prevent sample denaturation or evaporation, and a system case has the interlock to prevent from operators injury. The flushing method is pre-programmed for protein or DNA/RNA samples to eliminate sample carry-over, and the method is also customizable with up to three flushing solvents. The system allows samples to be recovered after measurement, and batch data processing includes secondary structure and comparability analysis.
• Fully automated measurement of up to 192 samples (two 96-well microplates), or 120 sample vials
• Pre-registered flush method for protein or DNA/RNA samples can be selected to eliminate sample carry-over
• Retrofit capability to J-1500 CD spectrometer
• Flow monitor function to optimize the sample flow conditions
• Capability for performing simultaneous CD/fluorescence measurement (option, see the fluorescence section)
Application
pH and salt induced denaturation study of VHH antibody
This shows the result of stability evaluation of antibodies (VHH model) by comparing the CD spectra of native and denatured antibodies using statistical analysis. Figure 1 shows the CD spectra of VHH for solutions with different pH values, and Figure 2 shows the evaluation results for VHH structural changes with the pH and NaCl concentration.
qHOS program can quantify the similarity of CD spectra using a statistical method, and can quantitatively evaluate CD spectral changes associated with structural changes in proteins.
Figure 1. CD Spectra of VHH antibody
Figure 2. Relation between pH and NaCl concentration of VHH antibody
Figure 3 shows a plot of the t-value obtained by HTCD and Tm obtained by denaturation temperature measurement by MPTC-513. The high correlation between the t-value and the denaturation temperature suggests that a spectral difference test is a very useful primary screening method before performing a thermal denaturation analysis, which generally requires a great deal of time.
Figure 3. Relation between denaturation temperature and t-value
Special thanks for collaboration; Prof. Kouhei Tsumoto, School of Engineering and Institute of Medical Science, The University of Tokyo