FAST MIXING DEVICE FOR TIME-RESOLVED SYNCHROTRON X-RAY-SCATTERING STUDIES OF RADIATION-SENSITIVE PROTEINS

A fast mixing device apparatus has been constructed to study the kinet ic structural reactions of radiation sensitive proteins by time-resolv ed small angle x-ray scattering. The sample cell has a volume of 0.75 ml and is translated through the synchrotron x-ray beam as the experim ent progresses. The dead time of the device is 50 ms, and it is able t o mix viscous liquids with ratios ranging from 1:1 to 1:250 with a mea sured precision of 0.1 mu l. The device uses two motor driven syringes that are individually controlled. The whole instrument is thermostate d and is remotely controlled. Cleaning of the cell is carried out remo tely, removing the need to enter the x-ray hutch between each measurem ent. Commissioning of the apparatus was carried out by following the a ssembly of the radiation sensitive protein tubulin into microtubules i nduced by two different chemical jumps. (C) 1998 American Institute of Physics.