Time-resolved SAXS Studies of Macromolecular Folding
Lois Pollack
Applied and Engineering Physics, Cornell University
Small angle x-ray scattering is an ideal tool for monitoring the transient structural changes that occur as macromolecules fold into their biologically active conformation. We have developed microfabricated mixers that enable rapid triggering of folding of both proteins and RNAs. Within these continuous flow mixers, time resolution is achieved by monitoring macromolecular conformation, via SAXS, within small sections of a flowing stream. At flow speeds of order 1 meter/second, each micron of length along the flowing stream reports on events occurring on the microsecond time scale. The earliest folding events, such as chain collapse, occur within microseconds. The time resolution of the measurement is limited by the mixing time of the mixer and by the total x-ray flux into a micron size spot. I will discuss the factors that limit time resolution, as well as the potential gains of using an ERL in conjunction with such a device.
