Optional programs and accessories – Linear dichroism

Couette flow cell unit

The most versatile approach to orienting macromolecules for LD measurements is the couette flow system. This system subjects the sample to a constant gradient over the annular gap between an inner quartz cylinder, which is rotating at high speed, and a fixed outer quartz cylinder. The CFC-573 Couette flow cell unit includes a built-in beam condenser, which focuses the beam onto the small LD flow cell to maximize light throughput. The cell unit is easy to install, remove and clean as needed.

• Applications to studies of proteins, DNA and biological or synthetic polymers
• Small (100 μL) sample volume requirements and 0.5 mm path length cell
• Continuously variable spinning speeds up to 5000 rpm.
• Temperature control using an external circulator

Schematic of the couette cell unit

With the sample in the annular gap, flow orientation is achieved by rotating the inner cylinder.


Couette flow measurement

Linear dichroism spectra of DNA from calf thymus measured at rotation speeds of 500, 1000, 2000 and 3000 rpm. The spectra were measured using data pitch of 0.2 nm with a scanning speed of 200 nm/min., a data integration time of 0.5 sec., and a 1 nm bandwidth.


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