Improving the X-ray resolution by reversible flash-cooling combined with concentration screening, as exemplified with PPase.
A significant improvement in the X-ray resolution of crystals of Escherichia coli inorganic pyrophosphatase at cryotemperature was obtained as a result of studying the relationship between the crystal order and cryosolution component concentrations. To perform the experiments, the ability to reverse the flash-cooling process and to return a crystal to ambient temperature was used. In each cycle, the crystal was transferred from a cold nitrogen-gas stream to a cryosolution with modified concentrations of the components. The crystal was then flash-cooled again and the diffraction quality checked. Such a technique allows the screening of a wide concentration range rather quickly without using a large number of crystals and allows the determination of optimal cryosolution component concentrations. The resolution limit for crystals of pyrophosphatase increased by almost 0.7 A, from 1.8 to 1.15 A.
Samygina
V R
VR
Institute of Crystallography, Russian Academy of Sciences, Leninsky Prospekt 59, 117333 Moscow, Russia.
Antonyuk
S V
SV
Lamzin
V S
VS
Popov
A N
AN
D018360:Crystallography, X-Ray / Q000379:methods*; D004926:Escherichia coli / Q000201:enzymology*; D005615:Freezing; D043564:Inorganic Pyrophosphatase; D009994:Osmolar Concentration; D011755:Pyrophosphatases / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012965:Sodium Chloride; D013816:Thermodynamics
D012965:Sodium Chloride; D011755:Pyrophosphatases; D043564:Inorganic Pyrophosphatase