Successful flash-cooling of xenon-derivatized myoglobin crystals

• Published in: Journal of applied crystallography Vol. 30; no. 2; pp. 190 - 194
• Main Authors: Soltis, S. M., Stowell, M. H. B., Wiener, M. C., Phillips, G. N., Rees, D. C.
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01.04.1997; Blackwell
• Subjects: Biological and medical sciences; Crystalline structure; Fundamental and applied biological sciences. Psychology; Molecular biophysics; Structure in molecular biology; Myoglobin; Hemoprotein; Method; Crystals; Crystallization; Xenon
• ISSN: 1600-5767; 0021-8898; 1600-5767
• DOI: 10.1107/S0021889896012939

This paper demonstrates for the first time a method for preparing cryocooled xenon‐derivatized protein crystals. The method is based upon the hypothesis and subsequent observation that the diffusion of a xenon atom from a tight binding site following depressurization occurs on a timescale of minutes. We have observed significant changes in diffraction intensities from myoglobin crystals for up to 5 min following depressurization from 1 MPa of xenon. In accordance with this observation, a xenon‐derivatized myoglobin crystal was cryocooled at ~95 K within 20 s of complete depressurization. A crystallographic data set was then collected to 2.0 Å resolution and isomorphous and anomalous difference Patterson maps revealed the presence of a well ordered xenon site with an occupancy of approximately 0.5. Phasing statistics for this site were of good quality and demonstrate the practicality of this method. The ability to cryocool xenon‐derivatized crystals will make this heavy‐atom substitution method even more useful for single‐isomorphous‐replacement and multiple‐isomorphous‐replacement phasing of macromolecules.