Circular Dichroism Spectrophotometer
J-1500 CD, Jasco
In circular dichroism (CD) spectroscopy, the absorbance of right and left circularly polarized light by molecules in solution is measured. Optically active, chiral molecules absorb one direction of circular polarized light over the other. This differential absorption provides information on molecular structure and its changes for small molecules, proteins and nucleic acids. For example, changes in secondary structure caused by protein unfolding (induced by perturbants such as temperature or pH), or folding (induced by the binding of a small molecule ligand, protein, or nucleic acid) can be quickly and easily quantified as changes in the far-UV CD spectrum. Separately, CD spectroscopy is also an essential technique in the study of chiral-selective properties of all molecules, including drugs, fluorescent dyes, and chemical catalysts designed to mimic enzymatic catalysis.
Features
- Scanning emission monochromator for fluorescence measurements
- Simultaneous measurement of CD, absorbance and fluorescence
- Automated titration system: titrates a desired solution into the sample cell while maintaining a constant volume
- Pelitier temperature control from -30 - 130°C
- Multiple acquisition modes:
- Wavescan from 163-950 nm
- Temperature scan, which collects a full wavescan or data at multiple wavelengths at every indicated temperature interval
- Fixed wavelength time scan for chemical denaturation and stopped-flow experiments
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Scan speeds of up to 10,000 nm/min allows rapid data collection
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Low noise (RMS noise < 0.007 mdeg at 200 nm) and very low stray light (< 0.0003% at 200 nm)
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Non-destructive technique
- 1 cm, 1 mm and 0.1 mm cuvettes available
Applications
- Protein folding and conformation studies:
- Estimate protein secondary structure composition
- Measure changes produced upon protein folding, ligand binding, or mutation
- Measure changes in stability in response to environmental perturbations
- Purity testing of optically active substances
- DNA/RNA interactions and conformation
- Drug development:
- Determine stereochemistry of chiral drugs and proteins
- Monitor ligand-induced protein or peptide conformational changes
- Gather information on binding sites
- Enzyme kinetics
Publications
Publications resulting from use of the J-1500 CD spectropolarimeter must acknowledge NIH S10 basic instrumentation grant S10OD036273.
Example acknowledgement:
CD analyses were performed at the Notre Dame Biophysics Instrumentation Core Facility with support of NIH grant S10OD036273
Internal Rates
- Unassisted: $39.00/hr
- Assisted: $104.00/hr
Left: Example temperature scan of a protein. Right: Wavescan of a β-helix protein.